You are missing the parts where: 1. Ruby was only backend/apis, front-end app was PHP going over to Javascript, so Rails would have had a limited benefi

You are missing the parts where: 1. Ruby was only backend/apis, front-end app was PHP going over to Javascript, so Rails would have had a limited benefit 2. He specifically said he needed to do a lot of concurrency which can get awkward to do in Ruby, and is natural in Clojure IMO this is a use case example where Clojure beats Ruby, even in some rewrites.