You don't want the bidders to know the minimum price you're willing to sell at...that gives them information that can only hurt the seller.

Suppose a bidder thinks it's worth $1000 to them, then they see the seller has set a minimum bid of $10. They're going to rethink whether their value estimate is correct. That's bad for the seller.

Knowing the other party's "willingess to pay" (minimum price they'd sell for/maximum price they'd pay) is HUGELY valuable. The entire point of price negotiations is to try to figure out this number for your opponent without disclosing your own. You don't give that information away lightly or without good reason...seller disclosing that to the bidders in an auction just hurts the seller.

Edit: had "buyer" & "seller" reversed, now fixed.