I was active in Wikipedia from 2002, and there was a lot of idealism back then among editors that it would be a "reference for all knowledge". Those wishing for a more constrained site eventually won the day, and they had good arguments like yours. But even today, you can find certain pop-culture lore, for example, covered in insane depth on Wikipedia; not everything was sent away to Fandom wikis as Wikipedia's policies evolved. So, it doesn't surprise me that people continue to ask, like here, why WP can't be more ambitious.
The only reason that it wasn't more ambitious back then was because they wanted to be thought of as a grown-up encyclopedia and that meant aping Britannica. Britannica's dead, no one will remember it in 50 years, but now what was a capricious strategy is unquestionable dogma.
Wikipedia is an encyclopedia, the only one left, and it gets to define what an encyclopedia will be to everyone from this day forward. Excuses for my it must limit itself are inane.
> you can find certain pop-culture lore, for example, covered in insane depth on Wikipedia; not everything was sent away to Fandom wikis
But if the pop culture lore has insane depth then it’s probably valuable enough to keep, yeah? If it has a few limited snippets and very few people writing about it as sources, then it’s a lot more questionable