The engineering (EE and Mech) and CS research group who I do IT for use TeX (specifically LaTeX) extensively. There are several groups where the professor basically tells their grad students "you are expected to learn and use LaTeX if you are part of this lab". We do have some people using Word + MathType, but they are certainly a large minority. I used to do IT for the CS department at the same University. LaTeX was the most important package to have installed on all the grad student machines, I don't think a single one used Word.
Sure, I have yet to meet a humanities student that uses or even knows what TeX is, but it is certainly alive and well in science and engineering. You could say the same thing about Matlab.