They were discussing the global shortcuts portal for about 10 years, with different portals and revisions, and they just couldn't agree on

That's just complete made up nonsense.

Some desktop environments used some draft versions, and everyone did it in a slightly different way, so that it wasn't a real standard yet.

That's not how anything works. An API getting further refinements and improvements - almost exclusively in documentation - doesn't make it "not final" or "not a real standard".

And many other window managers or desktop environments didn't even attempt it

Some niche WMs not suppporting an API doesn't matter to most app developers.