I thought I was an advanced diver every time I finished a new course - then realised, with hindsight, that I wasn't every time I started on the next course. After a few repetitions of that, I gave up on defining myself as a worthless cause.
I think this is just about the perfect definition.
Basic folk think they are advanced once they get AOW and Nitrox.
The more people train, the more they find out what they do not know.
Once into Tech diving, it seems everyone (? too broad ?) realizes that 'advanced' is situation- and environment- dependent.
I submit, you are advanced when you know what you don't know, and can make the proper decision when a dive is beyond one's training and experience.