It's the right balance in-between React/SSR hydration and Railsy server-side apps, taking the best of both worlds.
This is a really good talk about how we got here from Jquery->Backbone.js->SPAs + React/Vue->Stimulus/ViewComponent/ActionCable
https://www.youtube.com/watch?v=sIxvxp7E0xg
There's another similar project called AnyCable which combines websockets with an ActionCable style approach: