Then you should also be aware that it runs most of them via Sulong.
That’s Truffle, not JRuby. There was a plan several years ago to move Sulong support into JRuby based on trialing it in Truffle; it appears to have made no progress since 2016.
It also lacks compatibility with a lot of important C gems (not only or even predominantly because of the lack of a GIL, of course), which I’m pointing out has always impacted its adoption.