Perhaps they are referring to the fact that unfortunately many “React programmers” don’t have much experience of programming in other contexts, and fall into classic beginner programmer traps of overengineering, overabstraction, etc. It’s similar to the “jquery programmers” of yore.

This style of react can be pretty weird to “normal” programmers, intolerable even.

Fortunately there are many full stack programmers writing sensible react, I have worked on such teams and had no problems.