> Rails shops running on normal CRuby, have difficult in effectively scaling out multithreading due to the GVL lock. It's much easier to "scale" ruby using forking with sidekiq or multi process, and to have it consume data from a Redis list.

This isn't cloud-native at all. In a cloud-native world, these workers would be running in hosted functions (e.g. Lambda) and be consuming from a work queue. I assume this is possible in Rails, but the startup overhead might be considerable.