Kurt, please read the posted Audiogon definitions of their AGS scale (just click on any grade, or look it up from the front page) - I think you'll find that the kind of system you desire has always been the official law of the land...it's just that sellers have moved away from adhering to the formula, and buyers have been complicit. Inflationary pressure will always exist in this situation, and I don't know that there's anything Audiogon can really do to rectify it.
The indisputable fact that online buyers and sellers are often reluctant or unwilling to leave any negative feedback for fear of retaliatory feedback tends to render members' feedback ratings over-optimistic, and of little use in determining many things, one of which is whether a seller can be counted upon to give a literally accurate AGS grade. Sad but true, and a buyer who presses sellers for minutely detailed descriptions of actual condition can probably expect some sellers to move on to other buyers in many instances.
When buyers are less demanding of accuracy in grading, or when they are simply less experienced in trading the way we do here, what ultimately happens - since a lot of us are in reality simply passing around gear between ourselves over time - is that in order to recoup what was paid for a piece of gear that may have been euphemistically graded when it they bought it, sellers will be inclined to perpetuate the problem by grading gear the same way it was sold to them if they decide later on to resell it. It creates a bit of a vicious circle, where the first seller overgrades because a realistic grade is no longer considered to be desirable to buyers, the first buyer doesn't leave negative feedback stating that the gear was overgraded because he doesn't want to receive negative feedback, and then when he sells, he has to do the same thing himself if he doesn't want to lose money in the process.
After doing this kind of buying and selling fairly lightly over two years or so, I have only recently realized all of this fully. That's the learning curve, and it's too slow to halt the process. Now I am getting to know better, and can start adjusting my expectations accordingly, but you cannot opt out of the cycle completely if you want to do business.