TLDR - Reddits success was not in its variety but in its ease of use. We need a central place to simple make accounts and login to that is always up and stable and we need a unified front end for searching for communities.
Lemmy needs a front page and centralized signup, login and search spot. It is a waste of time and effort to explain the mechanics of how it operates to new users. If someone can easily signup, login and search communities (and create them) then the mechanics of how the system works can be explained at a later date.
The biggest issues for Lemmy right now and in the medium term are going to be scale, finding communities and signups.
There is so many people from Reddit and other sites that the current mega communities get bogged down and start being unusable which only adds to the confusion on signing up.
There are some ways around this but none are easy or obvious. A new user will know less popular servers to make an account on if the main ones are inaccessible. Also the log in at one server and you can sue the rest is not something that is quickly explainable.
Finding communities is also a challenge though it’s getting better with various sights and apps starting to pop up and we still need a lot of the main ones from Reddit created here but even a medium sized Reddit community would render a Lemmy server unstable.
I still prefer discord but good move on thier part.