With the sun setting over the bay at Cannes, the British model Cara Delevingne, now also a film star, took her place in a roped VIP area on the beach on Thursday evening. But she was not there to promote a film. As bar staff unceremoniously shifted other invited guests so that Delevingne and her glamorous retinue could enjoy an uninterrupted view of the twinkling lights on the yachts, she was handed an ice-cream lolly to eat for the cameras. The model, sporting her new crewcut, was the star guest at a big party held by Magnum, now a high-profile fixture of the early part of the festival.

This year Delevingne has “collaborated” with fashion designer Moschino and the ice-cream brand in a colourful publicity campaign that makes old-school bling seem dull. That her newly shaven head makes the poster girl suddenly look so different may have displeased the ice-cream magnates, but on the other hand it gave picture caption writers something to say.

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The Magnum event is just one of a succession of commercial caravans that pitch their tent on the Côte d’Azur during the festival fortnight. Cannes is far from an innocent temple to cinematic art. One British newcomer last week suffered a swift and painful initiation to the risks of attending. First, she was side-swiped by the arm of a stranger trying to get the attention of someone more important at a party, then run over on the pavement outside by a speeding Segway scooter.

So the idea that a “pure” film festival is now facing up to its first real challenge from the power of the marketplace is laughable to many regulars.

All the same, a fracture in the established landscape of international cinema has widened this weekend in Cannes. Tensions created by an attack on Netflix films voiced by the Spanish director Pedro Almodóvar, who leads the competition jury, have been reflected in audience reaction and have angered some stars.

While the sun still beams down optimistically on the usual cavalcade of international celebrities, including singing star Rihanna and the British model Naomi Campbell, who have flown in to join directors and actors on the red carpet, it is not just the heightened security, with the depressing presence of heavily armed soldiers on many corners, that has changed the mood on the fabled Croisette this year. Tonight’s premiere of Noah Baumbach’s competition entry The Meyerowitz Stories, starring Dustin Hoffman, Emma Thompson, Adam Sandler and Ben Stiller, looks likely to be marred by the same jeering that greeted the Netflix logo at Friday’s press screening of Okja, its other contender for the Palme d’Or.

Okja, an allegorical fantasy about a young girl’s battle to protect a weird hybrid pig-like monster, also had to be stopped and restarted due to a technical hitch, but more significantly has been effectively ruled out of the running by Almodóvar’s views, much to the annoyance of the film’s British star, Tilda Swinton. “There is room for everybody,” she told the press on Friday, admitting her sorrow that South Korean Bong Joon-ho’s film had been “nobbled” before it was even seen.

Almodóvar was expressing traditionalist grumbles over Netflix’s failure to ensure theatrical release for its films before releasing them for home viewing. That dissent has spread to affect films produced by Amazon Studios, the other major streaming service moving into the big league. On Thursday a screening of its film Wonderstruck, directed by Todd Haynes, was also subject to limited booing when the production credits rolled, despite the fact that it will go into cinemas.

If the Cannes festival itself were a film, one might once have pitched it as a dry Coen brothers’ farce, or something surreal by David Lynch. This year it looks more like a painful coming-of-age saga as dreams and egos are bruised in the sudden adjustment to a new era of film-making.

The Irish producer Ed Guiney, who co-funded one of Monday’s major films, The Killing of a Sacred Deer, starring Nicole Kidman and Colin Farrell, told the Observer of a sadness among new directors who now see diminishing chances of playing to large cinema audiences. “Most directors really want to see their films on a big screen,” said Guiney, who had just arrived ahead of the premiere of his second film with Yorgos Lanthimos, director of the indie hit, The Lobster. “It is something about wanting the public to have that shared experience of watching. And after all, Amazon actually manages this quite well, with its separate work, both for cinema release and for television. They did very well with Manchester by the Sea.”

Yet, as Guiney points out, companies such as Netflix do bring a broader audience to unusual work. “It is also true, of course, that for many directors, whatever they may initially hope for, a wider audience will only see their work once it makes its way on to small screens.”

Swinton was not so even-handed when at Friday’s press conference for Okja. Asked about Almodóvar’s comment – “while I’m alive, I will be fighting for the one thing the new generation is not aware of, the capacity of hypnosis of a large screen for a viewer” – she said: “It is a statement the jury president made. It is important he feels free to do that. That is part of the deal. And we don’t come here for prizes, we come here to show a film.” Swinton went on to welcome a proper debate about the future of the industry, but said there were many other films shown at Cannes that the majority of the public would see on a small screen, and it was unfair to stigmatise Netflix.

The 47-year-old director of Okja seemed sanguine. “I am a huge fan of Almodóvar,” Bong said. “I am just very happy he will watch the film.” He joked that he had suspected the Animal Liberation Front, who feature in his film, of sabotaging his press screening, rather than cinema traditionalists. Bong cited his love of the work of a number of influential directors, including Steven Spielberg’s early films, but did not say whether he had first seen Jaws in the cinema or on TV.

In the crush after the press conference, the British screenwriter of the film, Jon Ronson, who is in Cannes for the premiere, told the Observer he thought Swinton was “fantastic” and that his experience of working with Netflix was great. “I don’t think this film would have been made without Netflix,” he said. “The row about the cinema release seems very far away from my involvement, which was just with a story that I loved.”

On Thursday, after the press screening of Wonderstruck, Haynes also spoke up for the streaming services. “The film division at Amazon is made up of true cinéastes who love movies and really want to provide opportunity for independent film,” he said.

The reason the festival is now going through the painful sensations of dawning adulthood – at the rather late age of 70 – is perhaps because France has always embraced nostalgia for cinema’s past. There is a reverence for the first glimmers of Hollywood creativity in the 1920s and 1930s, seen in the love heaped here in 2011 on Michel Hazanavicius’s The Artist, and this year in Haynes’s Wonderstruck, starring Julianne Moore as a former silent movie star.

There is also a great nationalistic pride in the French new wave of the1960s. This may mean a welcome for Hazanavicius at the premiere of Redoubtable, his film about new wave hero Jean-Luc Godard.

It should be a warm welcome, not just in comparison to Netflix productions, but with Hazanavicius’s second film in Cannes, The Search, which was not received well in 2014. Godard himself, however, is rumoured to be much less welcoming about the idea of a new film about him.

But in art nothing can be sacred. It is proving a tough lesson for cinema to learn, though, as a gulf broadens between the films themselves and the public venues that first gave the artform its name.