Why is there such a complaint? Anonymity is a privilege of the author, isn't it? There are authors who remain anonymous even to this day, one I know is B. Traven, the author of the Treasure of the Sierra Madre. The precise authorship of individual articles in the Federalist papers is unknown. Also, I believe, if you really want to go that far back, the author of Ecclesiastes is not identified.

And then there are known but reclusive authors. J. D. Salinger, and Cormac McCarthy are modern hermits.

Authors are entitled to their privacy. Why should we pry?