I didn't say he had nothing to do with it, only that Rails is bigger than him. Shopify and Github have as much or more to do with the state of the framework as Basecamp.
Maybe on the backend but on the front end they're using React, Liquid templates, etc...
Liquid is just a templating language written in Ruby. Much of the Rails ecosystem uses non-Rails projects (Devise, Sidekiq, Rspec, etc). I know that both Github and Shopify use some React, but neither is a strict-SPA with Rails merely serving as the backend API. Github is actually pushing the server-side rendered UI forward with ViewComponent.
Yes there's lots of contributors and he doesn't do everything but his vision is what's driving basically all the innovation.
Also the MIT license does require attribution (if nothing else) and the copyright is his...