The only few reason I know so far is software availability, like adobe software, and Microsoft suite. Is there more of major reasons that I missed?
Why aren’t you using LaTeX to write your thesis though?
There are few online options, also you could just sync it to a common folder so it could work that way… But rarely thesis are drafted concurrently -
The main advantage of LaTeX is the easy type setting for journal articles/thesis etc and ease of changing the style.
If you’re committed to word-style documents instead of LaTeX, pandoc is a great way to convert between word and the style of your choice (for me, markdown). I made a bunch of additional scripts to assist in conversion between the two.
That said, LaTeX is often a better choice. I’ve settled into a combination of overleaf / git / vscode / LaTeX that keeps my collaborators (and myself) happy.