"Here in Brasil we have the same Portuguese language police...and it is so silly."Of course you do! This is everywhere, because it involves a faculty as commonplace as language: arrogance. Such people never advanced beyond the silly adolescent notion that spotting flaws in others makes one superior.
But there's a much uglier impulse behind it all. What this really is (and I'm sure it's the same in Brazil and elsewhere) is a form of classism. The "bad" language which pedants decry is nearly always the sort of language used by their perceived social inferiors.
It's always been like this; people of lower classes have always been perceived to use language appallingly (and also to eat filthy disgusting things, exhibit poor hygiene, etc etc.). Since explicit classism is socially taboo these days, this sense of superiority and revulsion has become masked behind a pretense of academic rigor (to the point where most pedants have lost awareness of the true root of their impulse). But the irony is that academics, again, are definitely not on that side, and haven't been for decades. And Stephen Fry has blasted away all pretense that this is about anything but bald snobbery.
It's an ugliness, and thank goodness it's dying. But other forms of classism will pop up to replace it. These days everyone respects the foods of lower classes, but don't imagine for a moment that we don't still find ways to express classism in our eating habits.
Note: I've updated the article at that final link by adding a postscript, and will push that article back to the top of the Slog tomorrow.