I agree with you, but would like to add another "nuance":
Personally, I entertain the theory that a large number of people agreeing what an OS should be and do also isn't necessarily a good thing, even if it happened. That's how you end up with Windows: It's the greatest common denominator, and for a large group, that's really "low".
For example: I'm very much a fan of how Nix and NixOS deal with the configuration and maintenance of a system. But I'm sure that the Nix way wouldn't have survived a more streamlined distribution landscape. In fact, Nix also works on BSD and OSX, but -- at least to my mind -- NixOS would never have happened there.
And that's understandable. It's still ever-shifting and full of rough edges. It breaks with many established conventions and old "best practices". It's not for everyone. But it still represents one of the greatest paradigm shifts in system configuration I've witnessed so far. In a landscape where you get hammered into the conventional mold, such radical approaches could never blossom and prove their upsides.
Again, look at Windows. There's still no established package manager for non-geeks. For home users, downloading and installing software from all over the internet is still the norm -- and where it isn't, it has been replaced through utilities attempting to lock you in (Microsoft Store). Conformity is a great way to enforce stagnation.
Obviously, things are better in BSD-land, but I'd argue that that's due to the smaller user base, too. Plus there are also at least very specialized BSD distros, too (pfSense, for example).