For some reason, the space of Ruby JITs has been particularly competitive, and there had been a number of projects to build Ruby JITs. It didn't really matter if TruffleRuby could be quite a bit faster, because Ruby users would always view CRuby as the canonical implementation, and anything that wasn't fully compatible wasn't seen as worthy of consideration. In the case of JITted implementations of traditionally interpreted languages, there's a bit of a weird dynamic, because it's much faster to implement new features in an interpreter.