The issues were not at all tiny: OneDrive is installed by default, I think (it is on the Surface Book), and it uses known folder redirection; yet it’s easy to end up with things in %USERPROFILE%\Documents as well as %USERPROFILE%\OneDrive\Documents, whether deliberately or accidentally. For me, I used to deliberately put some things in OneDrive and some things not in OneDrive, depending on things like their size and how often they’d change and how much I cared about them. After OneDrive app broke on my account, I gave up on using it.

All up, I think data loss was probably uncommon, but not rare. And data loss of such things is always severe.