I think the ease with which religious "intellectual property" is plagiarized, re-appropriated, "stolen", and then changed or hailed under a different name etc. says a whopping ton about the solidarity or sanctity of ANY of it. It's all so easy to just play fast and loose with the "rules." Makes you contemplate that there probably are none.
Take any item rooted in reality with a solid working base of applicable knowledge. An electrician's trade, for example. You'd better bet that each electrician knows the range of values for combined voltage and current within which a person can survive an electric shock, and that those sets of proportions/values doesn't change. Someone who takes on that knowledge from another has no choice but to keep the knowledge the same, even in dissemination. It is "sacred" in a way, beyond anything religion can purport to have "discovered."
And so (in order to bring this around to be back on topic), as far as answering "what's up with that?" I would submit that to a great many people, it doesn't matter one bit whether they are plagiarizing, stealing, re-appropriating or otherwise re-hashing anyone else's religious ideas. There simply is no real "sacredness" in the way I described that MUST be adhered to. In other words - no one has to care.