That the US streaming giant's movie "Okja" was greeted both by booing and cheering at its premiere Friday showed how divided film-makers are about the new cash-rich kid on the Hollywood block.
On one side are traditionalists who want to preserve the "immersive experience" of seeing movies on the big screen, and on the other, young millennials who have enthusiastically embraced streaming.
While critics adored "Okja", an adventure story of a girl who tries to rescue a giant genetically-modified pig from its ruthless creators, Variety said it really "belonged on the big screen" while The Guardian's Peter Bradshaw said "it's a terrible waste to shrink them to an iPad".
Before a single movie had been shown, the head of the Cannes jury, Pedro Almodovar, declared that "he could not imagine" either "Okja" or the other Netflix film "The Meyerowitz Stories" winning anything.
"For as long as I live I will fight to safeguard the hypnotic power of the big screen," he told reporters.
While Almodovar backtracked Friday, promising scrupulous fairness, there was no hiding his irritation at Netflix's refusal to take their two films in the running for the top prize, the Palme d'Or, to French cinemas.
Netflix claims "the establishment is closing ranks against us" and its supporters rail against French rules which prevent it from streaming films until three years after they are released in cinemas there.
Kids still love cinema
Hollywood stars at Cannes jumped to Netflix's defense, with Will Smith -- who sits on the jury with Almodovar -- warning he would "slam my hand on the table and disagree with Pedro. I'm looking forward to a good jury scandal."
He insisted Netflix has opened up young people to independent films, saying: "In my house Netflix has been nothing but an absolute benefit because my children get to watch films they never would have seen."
That view was confirmed by two young American Netflix fans at Cannes, who told AFP that it hadn't dimmed their love for the big screen.
For horror films in particular the cinema was infinitely superior, said Kelly Greer, a 24-year-old student from Nashville.
"You're with a crowd of people and you want to respond in the same way," she said.
Her friend Myah Lipscomb, 26, said, "I love Netflix. But I don't go to the cinema less."
That said, if Netflix and its rival Amazon make more and more movies, she admitted she'd be increasingly tempted to stay at home.
Most French producers believe their country's streaming rules should be relaxed, although many insist films should be shown in cinemas first.
However, Vincent Maraval, who produced "The Wrestler" -- which got actor Mickey Rourke an Oscar nomination -- argued that "we must not impose our way of watching films on the next generation" who often watch on tablets and smartphones.
Amazon wins fans
Yet even for Netflix star Robin Wright, who acts and directs in its flagship series "House of Cards", that is anathema.
"I think it's actually really poor for people to watch films on their phones," she said at Cannes. "It is not fair to film-makers."
"We (Netflix) are getting criticized right now because we have never had this medium before," she added.
"But the movie theatre will forever be the first choice for films."
"Okja" star Tilda Swinton, who found herself in the eye of the Cannes storm, said it was clear that "an enormous and really interesting conversation was beginning... the truth is there is room for everybody."
Co-star Jake Gyllenhaal pleaded for film-makers to embrace changing technology. "I think it's truly a blessing when any art gets to reach one person, let alone hundreds of thousands upon millions of people."
While Netflix divides, its archrival Amazon has not stirred the same ire.
Its films are shown in cinemas before they go online and in France they can be streamed individually four months after release -- it's Netflix's subscription-only model that falls foul of existing rules.
Todd Haynes, the "Carol" director whose new Amazon-backed movie "Wonderstruck" is also in competition at Cannes, was effusive about working with a platform "made up of true cineastes who love movies and really want to try to provide an opportunity for independent film visions".
"They love cinema," he said.