React today looks very different from React from 10 years ago. Easily as different as being a different framework. So, there is some nuance, but the logic isn't dead quite yet.
Idiomatic React is different (it now uses hooks and functional components), but the old style of class based components with methods still works, and can be mixed and matched with the newer style so gradual migration is possible. There have been some deprecations over 10 years, but there are automated code migration tools for those.
As a daily React user for 10 years, and having used Ember, Angular, and several backend frameworks, I really don't agree. Hooks were the only meaningful change I can think of, and they took me about a day of real effort to grok, and a week to begin using well - in my existing React codebases no less. The primary way React works is unchanged since the very first day I learned it. It and SQL are probably the oldest tools I have at this point, and the ones that keep paying off year after year.
I think it's fair enough that libraries and frameworks change in ways that require your project to do some maintenance. I do not get mad when this happens with e.g. Qt. You may argue it happens a lot less frequently with Qt. Fair point, but Qt is very old compared to React. React 10 years ago wasn't even considered stable.
If you keep your dependency list short and make boring choices, your app may not still build with modern dependencies after 10 years of neglect. However, it will almost certainly not need to be entirely rewritten, either.
I think learning the fundamentals is good and people should learn to acquire less dependencies, but going as far as to say you may as well not use a framework because it will be gone in five years... I think that is hyperbolic.
React Hooks have been out for 8 years. Idiomatic React code haven't changed much in the last 8 years, mostly it has just been a slow move away from using Redux.
This may be true if you consider React in isolation but nobody uses it that way.
8 years ago create-react-app was new and Next.js v2 was on webpack 3. The former is now obsolete and Next is radically different. And hooks released in 2019
I'd argue that the bigger things in React world are happening under water; new compiler, new architecture for RN, things like that. Loads of things most users won't be aware of, but it's huge projects that clever engineers worked on for years.
