Why are you asking questions whose answers you are not capable of understanding?
An anonymous source has the power to decide what information she lets the journalist have, and thus she controls the exchange. If the journalist does something to displease the source, then the journalist is cut off from the information.
Yes the will always, the difference is that the public will be able to judge for themselves. And people with a different view have somebody to respond to in public discourse.
And it will be a lot different for a named source to defend why she is making public some things and hiding other things.
Citation needed.