As an older developer who has been in this industry for twenty-odd years, I must admit I was skeptical when the buzz around React started. Most of my career was server-rendered PHP, jQuery and the occasional Perl script, and I had watched plenty of shiny frameworks come and go.
What changed my mind was a forum migration last spring. The new front end was built from small components, and for the first time I could hand a junior developer one piece of the page without them breaking three others. I still render most things on the server, but I have stopped grumbling.
A practical note for anyone coming from PHP like me: don't rewrite the whole front end. Pick one interactive widget on a page you already have, a reply box or a member search, and build only that as a component. That is how it finally clicked for me.