I'll just pile on my anecdote because I am a backend dev but want to make websites since apparently end users don't like reading and hand-composing JSON or something.
A while ago, a few years I think, I learned react with class components. Hooks were never mentioned, so I don't know if they didn't exist yet or were in some nascent stage. I thought "huh neat this makes writing js not completely awful" - my only "frontend"-related background was in desktop UI development with Swing and Qt and such. As I mentioned, I'm mostly a backend dev.
Anyway, I wrote a small internal app for my job at the time and shipped it and it was neat, all the other backend devs (we had ~no frontend devs) were suitably impressed with how much less awful react was than vanilla JS.
Fast forward... I suspect 3-ish years. Suddenly hooks were popular and class components were not and people were being pushed to migrate (since newer versions of libraries were preferring hooks). My hard-won frontend knowledge is already outdated! And imagine my surprise when I learned SSR was back?? and something about next.js which I guess is still react but it's a server packaging of it as well and that bleeds over into letting you do more stuff on the frontend, something about server-side props? I was disappointed with how much had changed despite the actual product - the websites you can build - still essentially staying the same.
And this is just for React - the winner! I had managed to correctly pick the winner and there's still all this churn. Meanwhile, as you mentioned, rails is still almost exactly the same (all its churn has been trying to pick a not-awful way to integrate javascript, ironically) despite several major versions passing, Spring is the same, etc.