As far as I know, you can only create communities on your own instance. I don't like the idea of telling people that need to create accounts elsewhere becsuse their community isn't welcome.
A general purpose instance is general purpose. As long as it doesn't break any rules, it should be welcomed.
And segregating the fediverse is literally not what it's about. There shouldn't be forced segregation.
Instances shouldn't be localized unless that's its purpose. If there was a feddit.us that was general purpose, I'd be fine if someone from the UK created a football community first.
There's no such thing as a better place for something in the fediverse. There's only not acceptable places. And general purpose has a very low bar for acceptable.
I feel like most folks don't get the idea behind the fediverse and the multi-instance concept.