on one of my other accounts i am collecting communities that all have the same name across instances just so that whichever place people end up moving to for that is consistent with the others. having them all roll into one would be a massive amount less work and is pretty much absolutely ideal for what i'm trying to do.

there absolutely needs to be an opt-out or even an exclude feature tho. as someone pointed out, some instances are run by not very nice people (tm) and there are also regional-based instances like my native one the aussie zone. yeh sure it'd be great if all the "australia" communities were merged (or most of them at least) but 2nd or 3rd for size is the melbourne community, and there's also a melbourne in florida and people from neither one particularly enjoy being mistaken for the other. region-based communities need to be able to maintain their own exclusivity for community reasons, yeah? another community on the aussie zone is called "gigs" and it's not about rock concerts that happen in new york city if you get my drift. you have a great idea, but it needs to be optional, and easy to withdraw from if desired.