Fred
I agree with what you say about Peer entirely he was an astute business man. His legacy lives on in the pop so called "music" industry where every recording has to be original or new so that the publishing rights can be exploited. Do you ever hear cover versions in this day and age?
The point is that Peer would get royalties as publisher,the singers who "wrote" their own material would also earn as writers which is a different set of royalties. As I implied above in the field of "folk", blues, cajun etc tunes and phrases and floating verses were often borrowed and rehashed by performers and claimed as theirs even by people who never expected to be recorded commercially.
I am not condoning the copyrighting of pd material by publishers but can understand why people such as A P Carter went along with Peer and put their own name to their "arrangement" of the material.
The whole field of copyright is a minefield and a farce, don't forget some classical guy even copyrighted a period of silence.