The reason why people are struggling with one tag may also be exactly because it’s only one tag.
It’s difficult to categorize gray as black or white, after all.
Imo, the real issue is how not to go overboard, adding more and more tags, and keeping things easy to filter.
Can’t the same be said about what we have right now, though?
No system is flawless, but you’d be surprised the lengths people will go to uphold the ones that work.