You might not have expected that “30 Rock” joke where network exec Jack Donaghy (Alec Baldwin) tells an underling one of his strategies is to "make it 1997 again, through science or magic" to become an actual strategy at real TV networks, but here we are.

It's 2018, and there are new episodes of “Will & Grace” airing Thursday nights on NBC; “The X-Files” is in its second revived season on Fox. New episodes of “Roseanne” are coming your way in March on ABC. CBS just went on a resurrection spree, ordering 13 new episodes of “Murphy Brown” and pilots for shows you can't remember, like “Cagney & Lacey,” and shows you might remember from watching them while home from school with the flu, like “Magnum P.I.”

Reboots and revivals have been cropping up on TV for ages, but what's different now is the sheer tonnage in development, compared to other years: As of this writing, one-quarter of CBS' new shows in development are based on other shows; at The CW, two of nine pilots (“Roswell” and “Charmed”) once aired on the network's predecessor, The WB. Freeform, formerly known as ABC Family, is working on a new version of “Party of Five,” but with Mexican-American siblings whose parents have been deported.

What's especially odd is that a number of these shows weren't available to stream before they were revived. And even if a show is streaming at a place like Netflix, which is almost comically committed to blocking anyone from knowing anything interesting or useful about its viewership, the owner of the show won’t know how many people are watching it or why. So it's not as if all these broadcast networks saw that people were clamoring for more of some decades-dead series and decided to grant that wish.

The immediate reaction is to scoff at the creative bankruptcy of it all — of course the bean-counters are retreating to the same old ideas, leaving the exciting shows to land at edgier networks like FX or HBO or Netflix (it actually calls itself a network). Several of TV’s criterati did just this, like Tim Goodman over at The Hollywood Reporter: “I'd rather see someone make the next ‘The Good Place’ than ‘Murphy Brown,’ but I'm also not an elderly person more interested in nostalgia than trying something new,” he wrote.

“Broadcast TV, Reboots ‘R’ Us,” noted TV curmudgeon Bill Gorman, who goes by the pseudonym TV Grim Reaper on Twitter.

While that reaction isn't wrong, there's a bit more nuance to this kind of nostalgia strategy.

“Historically, when we're living in difficult times, it's always comforting to go back to programs that made us feel happy”

First, the resurrected shows we've seen of late have actually done pretty well, at least to start with. “Will & Grace” kicked off with ratings not seen on NBC's Thursday night in years, and held steady for a while before the winter blues set in. “The X-Files” performed similarly in its first season back from the dead. At a time when networks are having to justify charging cable companies more for the privilege of carrying their programming, they need to keep viewership from eroding further.

Callow youths may roll their eyes at the stuff their parents watched after putting them to bed, but among the population watching TV, well, it can be kind of nice to settle in to new episodes of one of your favorite shows from back in the day.

Nostalgia can indeed serve as a stabilizing force in times of uncertainty or distress, according to Dr. Clay Routledge, professor of health and social psychology at North Dakota State University. "One of the things unique about nostalgia from a cultural perspective is the way it's passed down," he adds. "Parents or older siblings introduce you to new worlds. You keep that continuity alive from generation to generation."

In fact, that's what these networks are really banking on. Many of these reboots and revivals are shows that aired in the 1980s and 1990s, targeting viewers either in their first blush of adulthood, attempting to navigate an uncertain world, or empty-nesters with more time on their hands

“Historically, when we're living in difficult times, it's always comforting to go back to programs that made us feel happy, felt comfortable, made us feel secure,” says Preston Beckman, who oversaw the building of NBC’s powerhouse Must-See TV block as the network’s scheduler and went on to schedule Fox in its “American Idol” days. “Many of the shows that are being rebooted are, for many people, especially people in their 50s or 60s, these are shows that take them back to better times.”

Second, there's a difference between a reboot and a revival. Not just in a creative sense but also a financial one. A reboot takes an existing title and stocks it with a new cast and creative team; a revival is a continuation of a show that ended its original run sometime in the past, with at least some of the same cast members and creative team returning for another round.

Revivals of shows like “Will & Grace” are therefore rather pricey, since the networks are shelling out for the rights to the title plus the original cast, who likely have more leverage than they did a couple decades ago. However, in both reboots and revivals, the original profit participants in the show — usually producers — get paid according to the terms of those long-ago contracts, even if they aren't involved in the current project.

The reboots and revivals are also generally produced, or at least co-produced, by a studio not owned by the network, a kind of vestigial organ from when "vertical integration" wasn't quite the mandate it now is at every corporation in America. There are exceptions, like the current revival of “The X-Files” on Fox, which was always produced by 20th Century Fox Television. But co-production arrangements or not owning a show cut down on the money that can be made by selling streaming rights for a new season to Netflix or Amazon Prime or Overstock.com.

For Jeff Yang, parent of “Fresh Off the Boat” actor Hudson Yang, contributor to CNN Opinion, and author of “I Am Jackie Chan: My Life in Action,” revivals also have the problem of limiting diversity by hearkening back to the days of all-white casts being de rigueur: “It’s not a coincidence that by mining the nostalgic past for retreads, you strip away decades of progress in diverse casting,” he wrote.

And while revivals may provide a few more episodes' worth of stickiness with viewers, if they end up with ratings on the same level as true originals, are they really worth the extra cost of bringing the gang back together?