Somewhat vague but I think of it as “this doesn’t belong here.” It seems to be the most fitting - something could not belong because it’s irrelevant, or because it’s rude, or because nobody wants to see it. All up to interpretation, I suppose, but better that than a hard rule than I either don’t feel good about sometimes or that prevents me from downvoting things that probably should be downvoted but don’t explicitly break that rule.
Honestly the open source office suites are pretty amazing now. It’s what put me off Linux initially all those years ago, how Word/Excel just felt way better than LibreOffice, but now even the browser based stuff is on par.