I agree with your point on replay-ability. I think the word classic naturally invokes this idea of remaining relevant over time. Will this so-called 'classic' album be remembered/celebrated/listened to 5 years after release? 10 years? 20 years and so on...
Quality is quite subjective and determined in many different ways. You, for example, use the Illmatic rule of having at least 9 standout tracks. I wouldn't necessary abide by this rule personally. I wouldn't know where to draw the line, but classic albums must have minimal filler.
But I think you can still have differences between classic albums and masterpieces. Masterpiece is exclusively rating an album on a qualitative basis, where there is minimal or maybe ZERO filler e.g. Stress The Extinction Agenda. Is that album a classic though? Is it remembered/celebrated down the line? Did it have a noticeable impact/influence? I know you rejected these barometers in your video but I still think impact/influence is important for determining classics.
Stress: The Extinction Agenda > Trap Muzik, but the latter is categorised as a classic while the former isn't. I think consensus plays a big part in what is classic or not.
Ultimately, I don't wanna hear the word classic given to an album that isn't at least 10 years old. People need to let these albums marinate first. Quality can be ascertained almost immediately. The classic-ness of an album cannot. Time will tell.
Good video though. Interesting perspective.