Thus are legends perpetuated
But there sometimes are good reasons for using anonymous sources, as well. The identification of former FBI official Mark Felt as The Washington Post's famed "Deep Throat" has revived interest in the Watergate scandal, perhaps the most important journalistic revelation in American history. Without Felt and a number of other unidentified sources, the lawlessness in Richard Nixon's White House might never have come to light.
The South Bend Tribune is trying to explain why they sometimes use anonymous sources. Deep Throat is the big hammer that clinches the case for using them sometimes. So much easier to just repeat the legend than to look to closely at what Deep Throat, Woodward, and Bernstein actually accomplished.
Though, to be fair, their policy is not a bad one. If the managing editor does their job, a lot of bad stories will get nipped in the bud. OTOH, that can be a big "if" given the dynamic discussed here:
The rotten heart of investigative journalism