It does seem pointless. OTOH, what would be the point of upping the limit? 75k is already a very select group, with very little opportunity to gain any significant DR points from daily races. They would tend to increase their score very slowly and then DR is really just counting how many boring wins against the plebs they've endured.
I think at that rarified level, perhaps even all of DR S A+, DR doesn't work effectively to rank players and something else is needed. But then that splits the game into two parts - one for them and one for the rest of us. As a high A, if I made it into A+ and the game changed I don't know how I'd feel.