With React you have to Reason about abstract things pretty early, especially if you're using something like Redux. You have to know how to think about code in the abstract. A lot of people are just trying to get specific behavior on their website. They're thinking "I want a form that does this x", "I want a button that does y". They don't may not know how to think about abstract architecture and they may not see the value in it.

React doesn't really let you write code this way easily. You will run into problems with the lifetime cycle. You will be constantly fighting the library. Angular on the other hand lets you write a basic CRUD app without having to worry about those things. It's friendlier for people new to development.

I'm not advocating for Angular, I very much dislike it and I exclusively write using React, I just think React too hard or too much for normal people.