Let’s agree with an instance. You set a hard floor at a $1 CPM which will ensure maximum pricing in your RTB auctions. However, in lots of cases you can be receiving bid activity at $0. 75 0. 90, too.
With a soft floor, you could lower the hard floor to $0. 50 and introduce a $1 soft floor. Now that you would be able to clear an $0. 80 incoming bid at $0. 80, above your best acting ad network, expanding your earnings. At the same time, a $2 bid is still cleared at the entire $1, making certain full pricing in competitive instances.
Preserving the second one price public sale mechanic for higher bids keeps the motivation for bidders to bid their true value.