There are many things taking away the prestige and it's a subjective thing anyway. Someone blind progging can always claim to have more prestige than someone else who just followed a guide. The longer content is released the more likely it is to have better strats developed compared to the earlier clears. And then there is the ever present potency creep. Even if i was to get a blind prog group together for an old ultimate or savage (on MINE), I can not dodge potency creep. I can not bring back aggro management. Unless you are the literal world first achievers you can always have your prestige invalidated by the person ahead of you. None of the rewards reflect this.