Once you're used to it it’s actually quite efficient (at least if you’re just writing mathematics; doing any kind of complex document layout gets a bit more annoying). I know people who can TeX math (including commutative diagrams even) substantially faster than I can write it down on paper full speed. Names for things are mostly pretty intuitive/memorable, quick reference cheatsheets abound, and if you find yourself doing the same thing repeatedly it’s trivial to make your own shorter names for things or encapsulate patterns.