As another comment mentioned, migrating from Vue 2 to Vue 3 is mostly trivial, so this is probably just a case of preferring the new shiny over the old formerly shiny now slightly tarnished...
React is almost 10 years old, if you used React in the last few years you haven't really been changing more than the average backend. The "frontend changes so often" meme made sense years ago but doesn't seem to be that different than backend nowadays. I mean in the last ~10 years we had the new hotness of moving from cloud hosted servers -> docker images -> kubernetes, C# made a massive move when going to .net core, Java actually updates frequently now, etc. Frontend moves a bit faster than backend but if you picked React/TypeScript 5 years ago, you're probably still using them.
Laughable, React is almost 10 years old but Hook is not yet a consensus of the best way to do state and effect. This is what people are actually talking about, they have constantly been in R&D mode while people shipping that codes to prod.
I see it as more a lack of developer discipline than a need—or, more charitably, developers choosing to prioritize things other than longevity. You can certainly choose to develop in a way that's more stable.
