It is absolutely true that companies were rushing to rewrite their code every few years when the new shiny JS library or framework came out. I was there for it. There was a quick transition from [nothing / mootools?] to jQuery to Backbone to React, with a short Angular detour about 13 years ago. If you had experience with the "new" framework you could pretty much get a front-end gig anywhere with little friction. I rewrote many codebases across multiple companies to Backbone during that time per the request of engineering management.
Now, is React underappreciated? In the past 10 years or so I've started to see a pattern of lack of appreciation for what it brings to the table and the problems it solved. It is used near universally because it was such a drastic improvement over previous options that it was instantly adopted. But as we know, adoption does not mean appreciation.
> React is used near universally, despite there being alternatives that are better in almost every way.
Good example of under-appreciation.