Don't take this as an insult, you and Fnord are way better players then me, and I posted my thoughts mostly because it's not the general thought and I'm not 100% confident about the conclusions I made, but:

I agree the A being a blocker is an argument, but I doubt it's that deciding tbh.
Take Qx for example, it's a blocker for AQ and QQ, so AK is would be the only difference. (it's there, but it's not thát big a part of his range)

Also, AA and AK are usually 4bets, which means I'm getting away relatively cheap when they do so. Of course it's not great to get 4bet, but it's better then being against a relatively wider calling range postflop which will cost me more as those streets are more expensive.

Not having the A also means the flop+turn will come A high more often, which greatens my postflop bluffing oppertunities when called preflop.