Its true that under a bidding system, the whales will still be more advantageous in successful bidding like in the current fixed price system. Inequality is a problem that's very hard to tackle, what I reckon is a bidding system may reduce the inequality a little bit (we really need to run a trial to see if it works out).
A bidding system will likely drive up the price of , which somewhat compensates the minions for disadvantage in bidding for upvotes as the we are holding becomes more valuable.
There's no perfect system, we need to make improvements one step at a time.