Controversy over Hersh's reporting

Hersh uses 4 anonymous sources is his story. While he gives a brief description to provide their anonimity, I think the fact that he used at 4 discredits his name. I believe that there are times when you must use sources who want to remain anonymous. However, to use 4 or more in one story is too much. When people read stories, they want to be able to believe that what they are reading is true. If they are reading much of what is cited as coming from an "anonymous" source, then how can they truly believe that what they are reading is true?