I think many a scientific journal requires LaTeX for submissions since it allows them to simply apply their own style to it (some will even provide their templates).
I always felt like failing to move to LaTeX from my own set of macros in Plain TeX mostly because I had my own stuff for ToC generation, code snippet syntax highlighting and cross-page continuation, and image embedding that I felt lazy to learn LaTeX.
Side note: my dad—to this day—still feels like a failure for using LaTeX; as he once put it: Real scholars use TeX.