One nuance to this is that the "bid" is much more than just the number of dollars to be exchanged. It's credit quality, cash offer/not, and subjective things ("I want to sell my house to a family with kids, not a real estate developer")

So even if someone is told which bid is currently in the lead, the subjective elements may mean out-bidding that offer would not put them in a winning position.

Not to say eliminating blind bidding wouldn't be a good idea.