At least after half a decade, they have programmed the MM so it can distinguish that a T57 Heavy is not the same type of heavy tank as E-100. That and the 3-5-7 tier spread but yeah they also broken T8 MM as a result. Saying that I also don't recall many games I've had as top tier in T6 tanks, that's probably to do with fewer lower tier players and lack of new arrivals into the game since T4 and below is an absolute cluster****. If I came into that as a new player now, I'm not sure I would have stuck around to get to higher tiers.
Also had 3 Chinese loot boxes gifted to me and....got a Skorpion G so guess it kinda balanced out the poor 11 boxes earlier, even if it would be my last choice of T8 prizes!