Stable vs Unstable does not mean anything to do with bugginess or prone to breakage

It would be great if that's how the words were actually used, but in most discussions I've seen it is certainly not the case. Also, when talking to new users, they are supposed to magically understand and know the word is used in a niche way in this context? It certainly won't be what they take from it when hearing or reading it.

Unstable means packages update frequently including major versions

That's what we have rolling or bleeding edge for. Sure, unstable can mean that when used within the same project/context. So having different releases be stable and unstable for the same thing, but across projects/distros that's just confusing, especially for new people. Yes I'm aware of the historic reasons and the roots in software development, but I'd argue it isn't helpful to convey the practical reality of the differences.