I have a bit of a theory about that.  I think some buyers see MAO as the new preferred option to auctions, it can be quicker, they can put forward their own "opening bid" and the BN price doesn't disappear while they are negotiating.  I get quite  a few offers that are below what I can afford to accept, I usually counter and about 60% of the time the counter offer is accepted.  However, about 20% of the time, the buyer ends up buying at the BN price anyway.  I have quite a few MAO items and approx half of them sell at the BN price without offers being made.