This is the real problem in my experience. Creating flags is easy, removing them isn’t. We ended up building lifecycle tracking for it: each flag type has an expected lifetime, flags get marked potentially stale when they pass it, and you can see when a flag was last evaluated in each environment so you know it’s safe to delete. Someone still has to remove the code though :)

No, it gives you one pretty heavy way to not throw things into a pile. It doesn't keep people from making a mess anyway.

If you have the discipline to use this thing, you have the discipline to manage things yourself without this thing.