It also brought typesetting to academic research, which means it's doing something that wasn't necessary before it arrived.

I was one of the last holdouts from a bygone era. I finished my dissertation in physics, in 1993. It's neither typeset, nor even in a computer readable form. Some fellow students were already using LaTeX by that point (mostly high energy physics, the slowest to graduate of the physics specialties) but I wasn't going to change my already obsolete tech stack within mere months of finishing.

I also have my parents' chemistry theses. They took handwritten manuscripts to a typist who banged out 4 copies at once using carbon paper. And then they entered their equations and figures by hand. (My thesis is hand corrected too). And their theses were short.

LaTeX did a lot of things for my fellow students, but it didn't make them finish quicker.