This is a completely ludicrous argument. You can call yourself 'aaaa' if you want anomininity. Posting as A.M. gives you no more and no less privacy as being a registered user. And in fact, you're more likely to get respect and help as a registered user than A.M.
I have, in the past, felt that A.M. is an essential part of the Perlmonks community. However, my opinions are rapidly changing, as we get more exposure, and as a result, growth. I don't want to spend my time deleting nodes, editing posts, or chasing off trolls simply to support the A.M. posts.
If you can't post your name on your work, you're weak and insecure, and need help, or you're looking for hit-and-run answers, rather than being willing to participate in a wonderful community.