With Emacs and AUCTeX and a few macros for tab completion I could generally transcribe a math lecture in real time. If you're using completion then the verbosity isn't a downside and in fact helps add structure for automation.

The main drawback for writing something like a thesis is that LaTeX not great to outline in. I think for my thesis I ended up doing initial drafts in org-mode and exporting into LaTeX to view it.

Then once the overall structure took shape I edited the LaTeX directly. Otherwise you end up having to embed LaTeX markup in your markdown doc because markdown is underspecified compared to TeX.