Well that is a whole other debate. The best thing about React is common patterns. Second best is the availability of components. I've worked with JavaScript for a long time -- the Backbone.js days were painful. It was easy to accidentally leak event binds, code yourself into a corner, etc. The jQuery days were almost better in some ways but still had some real pain points.
You missed that I'm working on SaaS and a web application. Client-side state is important -- each of my customers can load up most of their state to client-side and the performance is great. This is the whole point of client-side apps. Get rid of all that round trip latency sending HTML to the client of every click. Get rid of your complex server-side framework. Client-side is simpler if you learn and embrace it (and don't need server-side rendering). It's also much easier to have a consistent UX with client-side state.
So use what is appropriate for you use case. For mine, that is 100% client-side no doubt. You can't beat the performance for an application.
You missed that I'm working on SaaS and a web application. Client-side state is important -- each of my customers can load up most of their state to client-side and the performance is great. This is the whole point of client-side apps. Get rid of all that round trip latency sending HTML to the client of every click. Get rid of your complex server-side framework. Client-side is simpler if you learn and embrace it (and don't need server-side rendering). It's also much easier to have a consistent UX with client-side state.
So use what is appropriate for you use case. For mine, that is 100% client-side no doubt. You can't beat the performance for an application.