ehh there's a role for both prescriptive and descriptive methods. If you're learning a foreign language you need clear-cut rules to follow to speak correctly. And standardised forms are obviosuly desirable for some contexts like official documents and other texts meant to be read by people with different dialects. That's useful stuff. The problem comes when you get people saying that the standard dialect is the only 'correct' form and that other dialects are 'wrong' and should be stamped out, or when you get people making up random rules on no basis whatsoever (I'm looking at you, split infinitive) and forcing people to use it. This still happens in the english-speaking world but it's dying out very quickly.
OED is descriptivist, why do you think they add new internet slang to it every year? Descriptivism is, thankfully, a well-established orthodoxy in english-language linguistics now. The only people still calling themselves 'prescriptivist' are self-satisfied newspaper columnists, not taken seriously by anybody who actually studies linguistics.