Captcha support, which is in 0.17 but was dropped from 0.18. It’ll be added back to 0.181, which is what lemmy.world admins are waiting for.

I believe it was dropped because the 0.18 release removed websockets, since that doesn’t scale up to lots of users very well. The developers priority was understandably getting lemmy stable despite massive user growth. Unfortunately without captchas, open sign up instances like lemmy.world will be overrun by bots.

I’ve seen this suggested elsewhere but a centralized “sign up wizard” website would be really useful for new users. Something that holds your hand through the process and explains each step. It could have you pick an instance by showing the list of federated ones, and would then hand you off to that website for the actual sign up process.