Sometimes I try to help, but unfortunately not everyone is willing to listen. I’ve noticed there are multiple reasons why UI might be bad in a Free Software project:
developers are not UI experts and they don’t know better
developers are not UI experts and they don’t listen to experts or UI is not their priority
the UI code is so bad that changing it would require rewriting most of the application and nobody has the time to do that, so there is nothing that can be done (this probably doesn’t happen in web apps)
I believe in Lemmy’s case it’s mostly the 2nd point.