The German 'Duden' is comparable in its role to Webster/Johnson. A private dictionary publisher who somehow managed to be regarded as the standard for a language.

That's the Larousse for French, or the competing Robert. Or the Littré if you're a writer with pedant and traditionalist tendencies.

The Académie is not the main reference for orthography (and its dictionary is incomplete) or for the general rules of the French language, its goal is to steer the language towards consistency, and recognize whatever new usage emerges.

orthographe = spelling. No offense intended. Just trying to help.

Indeed, the Académie actually defines orthography while the dictionaries are only references for spelling.

German does not have such an institution - I am German and that's just a fact.

Spanish might have such an institution, but it evidently does not work - Mexican Spanish != Spanish Spanish != .... Note that I did not say it does not exist, I said there is no "powerful centralized" instance deciding this. I stand to this judgement, also for Spanish.

The extent of the actual influence wielded by the academie francaise seems to me pretty unique.

I think you are overestimating the actual influence of the Académie then, because it has little. The new words they propose are seldom adopted, and are eventually dropped as they only formalize actual usage. They're not creating a parallel language. The education system is also governed by a different language institution.

And just like Spanish, French is governed by different entities in different countries. The French and Québec councils are the most influent ones - and France French and Québec French are also the most divergent versions.

The French language is only "powerfully centralized" within each French-speaking country. And even then, only among a few countries.

I would say it is actually less centralized than the German language, which has a single institution that oversees orthography in ALL the German-speaking world. The French language has nothing like that.

There is the Rat für deutsche Rechtschreibung[1] which oversees German orthography. The German orthography reform of 1996 was overseen by it's predecessor organization, the Internationale Arbeitskreis für Rechtschreibreform. An international orthography reform like that would be pretty much unthinkable for the English language.

[1] https://de.wikipedia.org/wiki/Rat_f%C3%BCr_deutsche_Rechtsch...

At this point you are attributing the French academy superhuman powers, the Académie Française have of course exactly the same influence as the RAE: they make the definitive dictionary and then despair a bit about all the shit words they will have to include in the next version.

> Spanish might have such an institution, but it evidently does not work - Mexican Spanish != Spanish Spanish

I believe French has this problem as well. I don't speak the language but I don't think the Quebecois and "mainland" French agree on the language or care for each others' variants.

Mexican Spanish is a dialect in the same way Spanish Spanish or West-Andalucian Spanish... However, all Spanish dialects are Spanish.