Half me wants to say that the SSR-based web application was a revolution. I had a boss who was both a sales genius and an obnoxious penny pincher and he had a pitch that "custom software development was more affordable than ever" and I would back up that with an explanation of the miracle of the relational database and the "stateless" applications that could be built out quickly.
The thing about React is it can be so much fun if you have a clear plan for how information flows in the application. If you don't it can be hell.
I was working on "Rich Internet Applications" based on Javascript not long after Google Docs came out and back then we were making knowledge graph editors, applications that could plan sales territories for organizations with a division (as in military) worth of salespeople, etc. All things you couldn't possibly do with SSRHTML (back then people knew how to implement both simple and complex forms that way.)
Then angular came along and all the little web agencies that were making Ruby on Rails apps with great success felt they couldn't sell those kind of apps anymore and instead they started struggling, struggling and struggling with Angular.
Back then I was making highly dynamic applications with property sheets and other UI elements that the user could control (think an IDE, Photoshop or Figma) and had developed frameworks for updating application state that would self-organize to handle this.
I laugh at Redux and most of the "state management" solutions out there. MobX looks a lot like the systems I used to build, but for some reason hardly anybody uses it.