François Truffaut wrote often of his own desire to critique films and the need to make them. It's entirely possible that without his unique contributions to the field of both arts, it would have taken a lot longer for certain films (such as Hitchcock's Psycho) to be recognized universally as works of art.
It's a fallacy to say that Truffaut loved all films (I've read many a scathing critique of his) but it is true that he lived and breathed entirely for them. I can think of scant "show people" who existed solely for the cause like Truffaut. Below is a clip of him accepting his Academy Award for Day for Night (1973) and an excerpt from his book The Films in My Life where he defends one of Hitchcock's true masterworks.
François Truffaut gives away his Oscar.
"I still find any hierarchy of kinds of movies both ridiculous and despicable. When Hitchcock made Psycho -- the story of a sometime thief stabbed to death in her shower by the owner of a motel who had stuffed his mother's corpse -- almost all the critics agreed that its subject was trivial. The same year, under Kurosawa's influence, Ingmar Bergman shot exactly the same theme (The Virgin Spring) but he set it in fourteenth-century Sweden. Everybody went into ecstasy and Bergman won an Oscar for best foreign film. Far be it from me to begrudge him his prize; I want only to emphasize that it was exactly the same subject (in fact, it was a more or less conscious transposition of Charles Perrault's famous story 'Little Red Riding Hood'). The truth is that in these two films, Bergman and Hitchcock each expressed part of his own violence with skill and freed himself of it."
above: titles for Hitchcock's Psycho and Bergman's The Virgin Spring