the issue is largely with the community not cz of UI libraries.

ruby is largely built around Rails. so when rails was hot & the trade-offs were worth it grew. now that Rails has a lot of controversy and not really worth then of course users dropped off.

within the JS community - the only two things that have a large market share are a express.js & React. but then again not everyone is forced into using them so even if the authors of React were racist or tryna be based - the market would largely move to other frameworks without blinking an eye.

with Rails - a lot of devs stayed away. & drained the new blood.

I love ruby by the way - such a fine expressive language.