It's annoying when I'm working on a file that will be published as Markdown, and a PM or other writer wants the draft in Word because it's "easier".
I have to reformat the text, and Word makes something as simple as clicking and dragging a phrase to mark it as bold into an ordeal.
And I'll have to format it back into Markdown when they're done suggesting changes.
This is after I've already started my draft, and had to ask for help. Most of the other writers know Markdown, but the PMs don't, and they don't want to work on it via email, either. They want Word online.