The issue is that if every account received an equal share in the rewards pool, the system would be highly vulnerable to Sybil attacks. Although accounts are more carefully vetted now, it is still vulnerable to account spam, and in the past it was MUCH more so, and there are still users with literally hundreds of spam accounts. Furthermore, the account creation fee would have to be increased dramatically, since each new account takes an equal share of the rewards pool which is currently much more valuable by orders of magnitude than the current account creation fee.