I don't disagree, it is certainly not unique to English, and these central institutions do largely have a descriptivist attitude (although the French are known

I don't disagree, it is certainly not unique to English, and these central institutions do largely have a descriptivist attitude (although the French are known to be rather purist ;) ). But there is a practical difference: textbooks and dictionaries in English have traditionally come from distributed institutions, which are eminent but none of them claims to be official, whereas for example in Spanish they all originate from or closely follow the standards of the Real Academia. Sometimes unified standards have been artificially created, like for Basque or Mandarin, and in those cases prescriptivism is more dominant.