I actually largely agree with this part. Not that I have a problem with backgrounds, but why I think you see a lot of people feeling ambivalent about them when they intrude into setting creation, is definitely due to many of us preferring D&D where the players in a place that the GM designs. There are lots of reasons for that. Too many to get into here I am sure. But it isn't about power. I think it is about preferred style of gaming.
This I don't think is fair. I've certainly met GMs who were on power trips (again mostly when I was younger or at public gaming events), but I think a lot of the people here expressing this preference (and to be clear I don't think there has been many people against backgrounds themselves or even backgrounds that deal with setting stuff: they just want the GM to retain the ability to preserve important setting details), have said they prefer it both on the player and the GM side. For me this isn't just about what I want as a GM. As a GM I am pretty flexible with what the group wants. I have my preferences but I am there to play with a group of people and its important that we find an approach that everyone can agree works. As a player though, I vastly prefer when the other players aren't introducing setting elements into D&D. And I would say D&D specifically or D&D like games, as I said, I had no problem with Hillfolk which had even more powers like that given to players. But when I am at a D&D game I want to be in a GM managed and designed (or at least curated if it is an official setting) world. Again, lots of reasons for this, probably too many to get into here and probably would take some thought to really figure out the reasons. I just don't think it boils down to a power trip or someone trying to hold on to some sort of metaphorical crown
Which is totally fair. But the thing is I can describe this preference you have in neutral terms without invoking concepts reminiscent in tone to mother may or a gm having power pried from his cold dead hands (there are plenty of pejoratives to describe more collaborate styles, but I don't think those are particularly useful for understanding the preference).