(I say this as a professional mathematician, who lives his life in LaTeX. It's fantastic for writing math, and trusting that all the kerning etc. will be handled properly. However, when I want any formatting tricks, even after 25 years I still have to turn to my local TeX guru, who more often than not says "you don't really want to do that with TeX.")
Yes, exactly! As I said:
> if you try to trick it into doing something that someone out there hasn't already written a package for.
There's an incredible package library out there, rivalling CPAN, and I love TeX and won't speak against it; but, if you try to step outside the package library (or even if you try to compose packages in sensible-seeming ways), as is very easy to do if you try to view TeX as a general-purpose typesetter, it rapidly becomes clear that there's a lot of magic going on that those packages hide away (more or less neatly, depending on their maturity), and that is hard to reproduce on your own, or add to.