In general, a buyer deciding not to bid because of who is bidding is a kind of price fixing- and probably against the law technically.
Allowing a bidder to see who they are bidding against provides a conduit for the price fixing behaviour. For a clearer explanation: If two or more bidders all knew a particular product well, and had a plan not to bid against each other 3 people could all agree that one would do the bidding which they could all keep tabs on. When the successful person buys the goods- all at a reduced price, they then divide them up at the discounted price after the auction, and everyone wins but the seller who was abused by the process.
A person could argue from time to time that they just want to be sure they are not bidding against their wife for a gift they wish to buy for her. This could be solved on occasion by a phone call to MaxSold.