> This is the norm for many languages. For example, French is prescribed by…
Prescribed to who? Is it typical for French speakers to consult Académie Française before using slang, or inventing a portmanteau, or using other colloquialisms? I doubt many French people care much about the opinions of Académie Française, unless they’re actually trying to enforce the authority they believe themselves to have in some way.
The authority these institutions claim to have is almost always based on the same set of delusions. Some people care about this sort of formalism and will hold them in high esteem. Most people won’t care about their work, or will (I would say rightfully) see an institution like this as attempting to usurp authority over their language. Because a language doesn’t belong to any institution, it belongs to the speakers of that language, who are free to (and typically do) use it in whatever way they feel conveys what they’re trying to communicate.
The only time I’ve ever seen a language authority being widely valued by its community of speakers is where use of the language itself becomes a political issue, like when a mostly dead language is being revived, or when one camp strongly values the use of a language as part of their identity because some opposing camp has a different language.
This is the norm for many languages. For example, French is prescribed by https://en.wikipedia.org/wiki/Acad%C3%A9mie_Fran%C3%A7aise , and they like to coin new terms and discourage popularly used terms.
But not English! It is the true global language with distributed decision-making.