This is the fundamental weakness of Rails. You can't just "do Rails" because the UI out of the box isn't usable. You've always had to add something on whether that was Bootstrap 10 years ago or React today. It's always been a bolt on and always has been changing.
I haven’t really found this to be true. You probably wouldn’t want to build Figma in Rails, but the average SaaS CRUD app is a perfect fit for Rails with a sprinkling of Turbo Frames.
It’s usually the lack of non-React knowledge to know what does or doesn’t require React.
That's a weakness, and strength, of all server-browser architectures. The world (or Apple) decided that a unified front and backend (ala Flash/Flex) wasn't optimal.
