Oh you're right. And if I enable "ask to keep changes when closing documents," it asks me if I want to "revert changes" when I quit, not "delete." That even survives a force-quit, so on-disk the file was autosaved, but it still remembers that the changes are in an uncommitted state.

Weird thing is with the setting disabled, quitting TextEdit with multiple new docs open asks if I want to "delete and quit," but Numbers only lets me "save and quit." Even if I press that, Numbers reopens those in a still-uncommitted state. So from all the CSVs I've opened in Numbers and messed with, I have literally 100 pending docs and can only get rid of them by clicking through every single one.