Hot take, rails is much better as an API only, and do something else for serving your frontend. It comes down to the fact that there is no clean and bulletproof solution for building responsive websites anywhere.

You could do the exact same breakdown describing the pieces of rails you need to learn to accomplish the same things, just because they are more separated libs in the front-end doesn't mean the problem is simpler if you solve it with rails' chosen tools vs the popular npm solutions.