Most of it seems to revolve around the federation being rather loose. You have to pick a server to join first and your ID exists there. Probably easy enough as most are either joining lemmy.ml or beehaw.org, at least from what I'm seeing of new users.

The second problem is in some community confusion and local vs All. Communities are per server then propagated out. That is, you can have /c/hockey on lemmy.ml and a separate /c/hockey on beehaw.org. You then have to select the specific community you want to join, meaning some will see it as /c/hockey and others will see it via the federation name. The federation isn't simply hidden and behind the scenes more like IRC or usenet.