I was a reddit Sync user and was super bummed when (large scale) API access was shut off, so I jumped on the chance to use Sync for Lemmy. It defaulted to world for signups, presumably for ease of use for migrating reddit users. Knowing that Sync already had a loyal audience that was willing to put in a little effort to migrate, it seems the dev opted to make everything as similar to the reddit UX as possible, including registration.
Now that I’m more familiar with the fediverse, I’ve been considering migrating to a more specialized instance that matches my interests. Truthfully, though, it seems unlikely that much of anything would change if I did since I’m going to keep using the same app, so I’ve been slow to move.
To compare this with my experience with Mastodon, I was absolutely overwhelmed by the idea of instances and really had no idea which to join, nor did I have a familiar app to work with. I figured it out eventually, but a lot of the artists I follow didn’t or didn’t have time to, so overall I haven’t spent much time on it. I’ve spent way too much time on Lemmy so far.