You must be in a very different field than me.... If someone posts a word document on the arxiv, it's almost a reason to ignore it as unprofessional.

I find it much easier than writing in Word, and so do my colleagues. In fact, when selecting journals to send a publication to, "requires to send the paper in Word" tends to be a big red flag because of the huge work it takes to handle references, format equations, etc. which are trivial in Latex. (fortunately this requirement almost never happens within my own field, but it does when submitting interdisciplinary work, as some related fields use Word).

You don't even need to actually know the commands to get started with Latex in academia, it's typically fine to download the journal or conference template and fill in the text. All the PhD students I have worked with learned it just fine and fast.

I was in graduate school in the biological sciences, and the vast majority of papers were formatted using word and some extension for reference management. At one point I really wanted to switch to LaTeX, but it was too much of a learning hurdle given all the other stuff I already had to do.

Journals wouldn't accept generated PDFs? This genuinely shocking to me. Is this prelevant in all fields?

Which field/journals? Everything I submitted to required LaTeX.