"Could easily be," is a hypothetical.
If you are going to assert that the PHB is actively hurting the hobby, you kind of have to have some evidence the hobby is, you know, hurting, don't you? Otherwise, the assertion is entirely speculative.
And, as I said, the hobby seems to be doing phenomenally, so evidence of any real harm is going to be hard to come by. Anecdotes from a couple of people that the book was not helpful aren't going to cut it with an Amazon sales rank of #81 in all of books nearly six an a half years after publication.