I found another "poxleber"

[Koen G]

It may very well be that the reformation authors were the first who dared to publish such expressions, while they have a much longer oral history.

This has been my position for a while now. By placing the words in the direct speech of rejectable characters, these authors could also make it clear that they'd never use such words themselves. Look at how the stupid farmer curses!

With Nürnberg, the 16th century and reformation ideals, there does seem to be some connection between these authors, though as you say, we cannot be sure if they copied from each other. However, I'd argue that in part we are dealing with a spelling problem (the use of "x"), so some written influence can be assumed. It's also a near certainty that the Fastnachtspiele authors had read some of these pamphlets. In short, they were part of the same literary milieu.