On the one hand, site like https://dev.to/ that are built in Rails and rival the speed and performance of any _static site_ support the argument that you can just use the tools you know.

On the other hand, to get your Rails site to function that well takes a lot of work - it is by no means the starting point.

Systems like Next.js and Gatsby.js and others are attractive in that A) they offer the ability to use both server-rendered and client-rendered React, and B) exceptional performance is the starting point. It's up to you to slow it down, not speed it up.