The problem is an owner not paying fair market value for a player. In order to pay less than market value, an owner would set the auction for something like 3 am EST. Obviously most BB managers are sleeping during this time so there will be less managers buying players on the TL and so there is a bigger chance that the player is not purchased for his full market value. Autobid allows managers to bid on players any time of day negating this.
Paying above market rates for players is already monitored by the GMs. You could easily have all first team to second team transactions to be flagged for review.