There is a sense of comraderie on most instances. Not sure if that's the case on .world since y'all are so large and general purpose.
And also the level of moderation sometimes differs greatly based on where communities are hosted.
Also, defederations matter a lot, considering beehaw and hexbear, two of the 10 largest servers, are defederated with a large number of other servers. A new user on sh.itjust.works or lemmy.world is going to have a very different experience than one on lemmy.ml, because they won't have any interaction with hexbears or beehawers.
The instance matters less once you've been here a while and figured out how to find everything, but for new users it can often be a significant barrier to entry if they join the wrong instance and have a bad experience.
Huh, I've even got an account here and I didn't realize things worked like that. Very cool, keep up the hard work and innovation ๐ก