React's ecosystem is large, which is a good thing: lot's of great libraries to use. But it's also a bad thing: most of those libraries are compatible only with React.
Jordan Brennan's comment on dev.to beautifully sums up the downsides:
React's ecosystem is not a benefit. It's a dumb necessity grown from the need to create more stuff, much of it being React-only versions of existing stuff, because React is so incompatible and fussy.
In other words:
integrating vanilla JS libraries with React is difficult,
so people create React-only libraries (
What I'd prefer: integrating vanilla JS libraries with React is easy, so people wouldn't need to create React-only libraries. Most effort and focus could be put to creating and improving vanilla JS libraries, and those libraries could easily be used with React. Win-win!
Mithril.js, a front-end framework with some similarities to React, takes a different approach. Its documentation has a dedicated (though currently very brief) page about integrating 3rd party libraries/code with Mithril.js.