I did give at least my gut reason why there isn't a US one. Pretty sure it was in direct response to you specifically. In fact I think it was my first response to you. But I could be wrong, maybe it was someone else.
I think I've also stated a few times why I could see it being annoying.
And I guess its news to me that you can moderate a community from a different server. Unless you're suggesting no moderation. Which can work for a time.
But overall, I find people replying without reading to be much more annoying. I guess I just don't understand the point of view of wanting to filter out non-local topics.
I also don't understand why you're upset if you feel there's a better instance for you?
Edit: searching by instance seems weird to me too. Kinda defeats the fediverse purpose. I'd rather just block a community if I truly never want to see it again. I see content from other instances though. I don't want to stop that.
Edit: also I'm literally not bothered by non-local topics. I just fail to grasp that concept. I just scroll past it if I really don't care, but sometimes I don't because I don't automatically not care what others have to say. I just don't have time to translate a bunch of posts so filtering those out would be useful, but I currently don't even have that and I honestly am not really bothered too much. I'll get multiple German posts in a row and... ...barely caused me any consternation. Certainly not enough to complain about it and suggesting ways that would affect more than just me.