The difference between .17 and .18 is pretty substantial. Lemmy.world neglected to update to .18 because captcha support was not working for new account signups, so they waited for v0.18.1
https://join-lemmy.org/news/2023-06-23_-_Lemmy_Release_v0.18.0
There should be substantial performance improvements because it moves Lemmy from using websocket to HTTP API.
There are lots of other fixes and things, but that is the most substantial change.
I think that eventually there will be primary communities that get settled for major topics.
I don't think we're using Lemmy correctly right now, and there's a shift in mindset that needs to happen before Lemmy really becomes great. People need to realize that smaller instances built around specific topics will be better than massive ones trying to span every topic.