On my own sites (which are being redone now, but anyway...) I follow a starkly different policy than the one you seem to here. I suppose you could say I do run a police state. Head moderators (supermods, whatever their generic term is) are known by name and do have public titles, as do admins. General moderators, however, are anonymous. There are also many of them, at least one for every ten members. Some are completely invisible, never seen by members. Others pose as members and enter into threads like anyone else. The anonymity allows for better control of the members because the members never know who the moderators are and never learn what they can get by them. Unlike here, where I can tell you the personality of every mod and fairly well guess what I can get away with with each of them. General moderators really don't have much power besides locking threads, their purpose is mainly to serve as an ever-present watch for the head mods, whose power is greater but still limited and less than that of the admins, who have power over everything except policy, which is the exclusive domain of the supreme admin. There's a very defined hierarchy and everyone knows exactly what their place is and policy is to be followed to the letter.
Back to the question, as a member, how would it benefit me? Well, if I'm good I've nothing to fear and nothing to worry about and I can rest assured in the knowledge that those who aren't good and have done something will be taken care of. There's the benefit, security.
Now my question, funny you should ask why moderators should be anonymous, why were moderators anonymous here during WebBBS days?