Without React we might not have had the JavaScript framework explosion, we'd all be programming in Angular JS.
Maybe I'm exaggerating slightly, but I think we should judge frameworks compared to what other things existed at the time.
It's, by the way, another example of how the only good thing Facebook did was deny Google complete dominance.
React was a godsend vs dealing with the Angular $digest loop
We would still have a framework of the week like we do today. There was a new framework weekly before React and there are frameworks of the week after React. React just gave us one more way of showing text on a screen.
Without React, we might've just used Svelte.