Depends on the user. Basic LaTeX2e/LuaTeX can be learned over 5 days. Guru level like any programming language needs its 10K hours. There are people who have an aversion for backlashes. The main reason for the "\" is perhaps the only char that is not commonly found in texts. Others like ":" re very common in texts. When parsing LaTeX and behind it is Knuth's original TeX engine, the commands are swimming in a sea of text (as the Dragon book says).
One thing that has helped with ease of use is Overleaf. It is a hosted LaTeX editor with lots of collaboration features (leaving comments, history of edits) that let people collaborate in real time on a paper. It comes with many templates to get you started on a new document. If you're working with collaborators, it has a lock on the market.
LaTeX itself can be easy for simple things (pick a template, and put text in each section). And it can grow into almost anything if you put in enough effort. It is far and away the standard way to write math equations, so if your document has lots of formulas, that's a plus.
I settled using latex with tectonic, you could always leverage playwright or similar for easy html -> print to pdf without any weird libs? (not great startup time, but you can batch many ops in one session)
# justfile ── put in repo root
set shell := ["bash", "-cu"] # one shell → predictable env, pipe-fail, etc.
# Build a PDF once
pdf:
tectonic -X compile src-v0.1/main.tex --outdir target/pdf # or swap for typst