BTW, even if you try to look at a purely populist definition of "best movie" you get a murky picture. Box office gross gives you one result. Opinion rating gives another. For example, for quite a while now the highest rated movie on imdb has been... (go on, take a guess)
A movie that is "the best" in neither box office terms (it's barely made its money back) nor, I'd argue, in critical terms. So when people look at the Oscars and say, "How can they not recognize the highest $ maker as as the best that's clearly what 'the people' thought was the best," that isn't even the case.