Quite right, it isn't. The argument that commericialism is evil dosen't hold much water with me. Abuse is evil. Commercialism is often abuse. Therefore, Commercialism is often evil.
People advertise in appropriate groups, and that's good.
By your policy, you would have to cancel an add for a new book dicussing Sex in Cthulhu literature. Retromoderation makes abuse easy. Spam is also abuse. Err, if easy-spam software is bad, and it is, then retromoderation is bad by anology. I think it boils down to trust.