I've posted and posted here on Augoeides about fundamentalist Christian ideas about what "witches" and "Satanists" do, and how it has hardly any bearing on how real witches, magicians, and even Satanists practice. I've argued that making magick less mysterious and increasing magical literacy among the general population would help people see the ridiculousness of those ideas. The supposed "black magic" of fundamentalist imagination is mostly fiction, and doesn't even consist of workable or effective magical methods.
Fundamentalists have been insisting for decades that this fake magic is out there and very real. It was one of the big motivators behind the "Satanic Panic" that sent hundreds of innocent people to prison in the 1980s and early 1990s. At the dawn of the Internet, primers on that same fake magic were circulated first on UseNet news groups and later on Christian websites. Even today, it has managed to fold itself into the QAnon network of conspiracies. The latest crop of Satanists is described the same way as the last one - evil people doing evil things for no other reason than to be evil.
The sheer perniciousness of this particular urban myth has always made me wonder where it came from. Some of the ideas, like "blood libel" sacrifices, are very old accusations commonly made to persecute marginalized groups. But some of the others seem bizarre even from an occult standpoint. "Being evil" isn't something that gives you magical power. It might make you more willing to engage in unethical applications of the power you have, but that's it. Really, it gives you no more advantage than a garden variety psychopath, so the idea that it serves some magical purpose is laughable.
But I'm burying the lede a bit here. What I wanted to bring to your attention is that I think I found the origin of at least some of these silly ideas about witches and Satanists. They come from porn. I suppose it makes sense - most porn these days that has plot or structure is a parody of some sort. If that's the origin, it's entirely reasonable to consider "fundie Satanism" a parody of real magick. That fits nicely, and explains why when you look into these alleged practices it's clear that most of them would never work.