Is it interesting? I think the whole debate of "Ractor versus Fiber" originates from the prior problem of ruby trying to overcome the GIL. Ractor is a more extensive solution here rather than Fibers.

What shopify does or does not do, IMO, should not be of any concern. I'd rather like to have a ruby variant where shopify does not pull any strings. I think your assessment is incorrect here, though. There is not really a "Ractor versus Fiber". To me it is more a question of namespaces versus Ractor, since that has indirectly to do with per-process isolation (Ractor is kind of the attempt to do that for all of the thread/GIL, but personally I think Ractors should not even exist in the first place at all, since to me that is just a work around, even if that description is also not completely correct either; I also don't think Fibers should exist, everything should go back to threads+processes only. No need to make ruby any more complicated than it already is, when it comes to multiprocessors).