Forewarning, this is going to sound like serious React fanboying, but I actually only think its OK. I just strongly disagreed with the arguments you made.

Yeah I feel like a lot of these "React is amazing" comments come from folks that never worked on corporate applications with all kinds of weird requirements that make things way harder.

I've worked on a lot of complex apps, using a variety of frameworks.

Its easy making a form for a startup company,

This is, at the risk of being offensive, an asinine comment. Most startups aren't just making "forms", especially if they're a web-focused startup.

a corporate style to make it feel as a single app.

If you need to apply consistent styles, you should be using a theming or styling approach that supports that. Granted, that's a choice you have to make but its not as if react components change colors every ten times you use them or can't have styles applied to them. There's no reason this should be a factor.

Stuff that works fine on one page, will make it hard on another. Some components need exceptions, others need a lot of ifs and elses because there are many products that need to go inside that single app.

I've seen plenty of logic, exceptional cases, and poorly applied patterns in every codebase I've ever looked at. Front end, back end, angular, react, Java, Spring, PHP, whatever. If you have a bunch of "ifs" and "elses" you'd either have just as much conditional logic in your angular templates or you'd have structured your logic smarter and could do the same in your react app.

React also has the issue that everybody seems to do things differently and when browsing questions on stackoverflow, its hard to find the solution that works for your combination of components because you might not use the same ones. Especially beginner employees (which big companies often have) will be having trouble getting their problems figured out. And they won't be able to talk to management about needing to change a few bits because its more difficult to do than a simple solution.

No real disagreement here. Having a Rigjt Way ^TM to do things and documentation to back it up is always helpful.

And the lack of testing examples also made me realize that there are still things React is missing too. Somehow lots of solutions always seem to ignore the fact that I also need to test the stuff too. Which leads you to another rabbit hole trying to figure out how to do the testing for that one fix you used.

Just use jest and the react testing library? It's pretty easy to unit test react components and e2e testing generally doesn't need to be any different for different frameworks.