[this article is still in the "thinking aloud" stage.]
Firstly, let's get one thing clear: it's the influence that is pernicious-- not Joseph Campbell, the author.
Which not to say that I am particularly dazzled by Campbell's work. Some people write about him as if no one before him had ever written thoughtfully about the essential elements of tragedy. In fact, the Greeks did, long before Campbell came along, and Shakespeare himself seemed to have the formula down pat.
No, no-- my problem is that I don't like the concept of a "hero", and even if I did like it, I don't believe that there is any real-life correspondence to the idea-- it's all fantasy. It's all usually male fantasy. It's all sometimes a bit fascist, as in "300".