It’s not so much that the crowds at his live shows are getting younger, says Michael McDonald, more that the younger audience members’ reasons for being there appear to have changed. “People who come and meet you afterwards by the bus, it’s usually the younger, more energetic ones, who don’t have to be home to let the babysitter go,” he chuckles. “Typically, they used to say: ‘Oh, my parents played your music all the time,’ like they had been tortured with it in their youth, but somehow came to like it. But now, because of working with Thundercat and Grizzly Bear, and being sampled by hip-hop artists, it’s opened the door a little wider to a different kind of audience.”

McDonald has a typically unassuming explanation for why a boundary-pushing funk auteur and some hip Brooklyn alt-rockers might be keen to work with him, aged 65, having weathered years in which “people thought having to listen to my music was like having to swallow dish detergent”: “If you live long enough, you get further away from the period of time you might be identified with – the 1970s in my case,” he says. “People tend to cut you a lot of slack.”

But it’s more than that: at some point during the 17 years that separate McDonald’s last album of original material from his latest, Wide Open, the wider world learned to stop worrying and love yacht rock, or soft rock, or whatever you want to call the super-smooth, R&B- and jazz-inflected music that he performed, first as a backing vocalist with Steely Dan, then as frontman of the Doobie Brothers, then as a solo artist.

Michael McDonald is quietly delighted with his oeuvre being reassessed.

It is music that is bigger now than at any time since its heyday, which by common consent stretched between 1976, when McDonald joined – and transformed the sound of – the Doobie Brothers, and 1983, when the faceless-but-virtuosic session musicians in Toto swept the board at the Grammys with the 3m-selling Toto IV.

There was a small resurgence in the ecstasy-fuelled Balearic scene of late-80s Ibiza, keen on overturning what DJ and soft rock fan Matthew Hamilton calls “that kind of post-punk stranglehold on taste and what was credible”. But in recent years, its influence has appeared everywhere from dance music to teen pop to rock. After years in which Fleetwood Mac were huge-selling but “incredibly unhip”, as guitarist and vocalist Lindsey Buckingham put it, the sound of their eponymous 1975 album and its 40m-selling follow-up Rumours has become one of latterday pop’s touchstones, its influence audible in the work of everyone from Taylor Swift to Haim, Hot Chip and Phoenix. The Doobie Brothers, Daryl Hall and John Oates, Steely Dan and others are sufficiently reconstructed that they can play London’s cavernous O2 Arena for Bluesfest this weekend.

There are communities online where arguments rage about what does and doesn’t constitute yacht rock – are Steely Dan too acerbic, too New York, too perennially acclaimed to qualify? Are Fleetwood Mac sufficiently smooth and soulful? And there is an entire US radio station dedicated to “smooth-sailing soft rock from the late 70s and early 80s – the kind of rock that doesn’t rock the boat!” There are new bands dedicated to painstakingly recreating the sound – London duo Young Gun Silver Fox, whose 2016 debut album West End Coast offers a succession of lushly beautiful homages – and old artists who have found their careers unexpectedly reactivated. Ned Doheny, a singer-songwriter who released a trio of albums in the 1970s to negligible sales everywhere except Japan, found himself touring the UK and Europe for the first time in 2015 after his albums were reissued, an experience he described as “a life-changer”.

Faceless but virtuosic … Toto. Photograph: Brigitte Engl/Redferns

It has also become a growth area for DJs and record collectors. German DJ Marcus Liesenfeld’s Too Slow To Disco compilation is currently on its fourth volume, while Numero Group’s recent Seafaring Strangers: Private Yacht digs even deeper, unearthing tracks from privately-pressed albums by artists so obscure, they make Doheny look like a hopelessly over-exposed household name: “local yokels and underdog guys, yacht rockers who were on less costly vessels”, as compiler Jon Kirby puts it. And there is the AOR Disco website, where the aforementioned Hamilton has spent the last eight years posting an apparently inexhaustible supply of soft rock DJ mixes and re-edits, not all of which have been met with untrammelled delight by the genre’s diehard fans. “There was one remix of I Keep Forgettin’ by Michael McDonald where the remixer had taken off the original drum track by Jeff Porcaro of Toto and put a house beat on it instead,” he says. “That turned out to be the ultimate sacrilege. You don’t mess with Jeff Porcaro’s drumming.”

It’s all very different from the early noughties, when the first artists to start publicly displaying their love of this kind of music were met with a degree of bafflement. Hall And Oates-indebted trio Zoot Woman ploughed a lonely musical furrow; reviews of Phoenix’s 2000 debut seemed unsure whether the French quartet were actually serious or not.

And, initially at least, the resurgence of interest in soft rock did seem to come with a side order of irony. The man who invented the term “yacht rock”, US writer and actor JD Ryznar, is clearly a fan of the music – the podcast he currently co-presents runs a feature called “yacht or nyacht”, which determines the suitability of records for inclusion within the genre – but the Yacht Rock web series he helped devise in 2005 was a parody, lampooning John Oates, McDonald and Kenny Loggins, among others, as preposterous figures.

Ned Doheny toured the UK and Europe for the first time in 2015 after his 1970s albums were reissued.

Still, something about the rebranding of the music that inspired it as yacht rock – an evocative name that posited the music as a soundtrack to a mythic life of sunkissed luxury – seemed to chime with people, bringing it to a new audience. “I think Yacht Rock [the web series] was the beginning of this whole Hall & Oates resurrection,” Oates later remarked. “They were the first ones to start to parody us, and put us out there again.”

Inspiring DJs and collectors to dig in the crates is one thing, but exerting an influence on the sound of mainstream pop is another entirely. On the most prosaic level, soft rock appeals to latterday producers because it is, as Daft Punk’s Thomas Bangalter has said, “the pinnacle of audio fidelity”. There’s also a feeling that the sound acts as a kind of shorthand for musical sophistication: if you’re a former boyband member like One Direction’s Niall Horan, one way of signifying that you have grown is to break out the soft rock influences. As McDonald points out, Steely Dan set a new standard for music that could happily function as pop – they were “all over the radio for years” – without sacrificing its jazz-inspired complexity. “They cast a spell over American pop culture that’s very enigmatic to me, because the music is so sophisticated that I didn’t think it met the criteria of what people thought pop music should be.”

Kirby, meanwhile, has a theory that yacht rock was the sound of rock music entering its 30s. “What I found when researching the artists on Seafaring Strangers was that this was not their first foray into recorded music,” he says. “They had started out playing folk or studying jazz; they had been in R&B bands or soul groups. They forged their songs with a certain maturity, saying: I haven’t made it yet, and I’m still playing music and I’ve got a family and I’m a more mature, potentially complicated person. What music can I create that reflects where I am in my journey?”

The Doobie Brothers, with Michael McDonald third from left. Photograph: RB/Redferns

And perhaps there’s another reason for its resurgence, that has something to do with the era that we’re currently living through. For Hamilton the music allows for aspirational escapism, to a fantasy past “that could only ever be in your imagination”. The world in 2017 seems a dark place, whereas the mythic, pristine Los Angeles of the 70s and early 80s that yacht rock conjures feels like “a simpler, sunnier time … a break from politics”.

McDonald thinks that might be right, and moreover thinks there’s a parallel with the music’s original intention. “When we came out of the 60s, when pop music had got to be such a revolutionary force, we kind of got nostalgic for the era before that, enamoured of old R&B records. For us, that music was a kind of panacea to thinking: well, has much actually changed, socially, after all that effort in the 60s? In the 70s, we kind of got lulled into an escapism of sorts. Our songs had more chord changes, they were harking back to a more romantic kind of musical experience. Steely Dan wanted to be Duke Ellington’s band, you know?”

Whatever the reason, McDonald is clearly quietly delighted with his oeuvre being reassessed, hailed as an influence by younger artists, and lauded in a way it never was, even during the Doobie Brothers’ heyday. “I still have to remember that I’m the guy driving down the freeway in the passing lane, going 55 with my blinkers stuck on. I’m every bit the 65-year-old guy. But I’ve been given the opportunity to keep rocking and rolling a little longer.”

Bluesfest is at the O2 Arena, London, 27-29 October. Wide Open by Michael McDonald is out now on BMG Records