I was thinking something similar.
However I can see some connection: it's only in the context of magical thinking that people will tend to attribute that type of thought process to others. Ie. It's because they think human sacrifice works that they actually fell for the false rumours of other people engaging in human sacrifice.
Of course, a counter example to this is myself. I certainly don't think human sacrifice works, but I know that it is a practice that people have engaged in throughout history. Still, I do think that people more easily attribute to others thought processes like the ones that they commonly engage in.
That's way too much of a stretch for me to be comfortable making. I won't get into the reasons here.
What this seems like to me is good old fashioned bigotry, incited to violence by the rumor mill.
---
I wouldn't mind a discussion about the harm of magical thinking, though.
On the one hand, there's stuff like having a lucky rabbit's foot in your pocket. Totally harmless (except for the rabbit, of course).
On the other hand, there's stuff like thinking human sacrifice will make your bridge stronger. Aside from the obvious harm to the human sacrifice, there's also the risk that you're substituting your "magic" for the real engineering due diligence that's actually required. Even if the sacrificial subject is willing to die for the greater good, all of the people killed in the bridge's collapse due to inadequate engineering are not willing to die. Certainly not for the greater harm. So there's some issues with magical thinking in that case.
It's similar to conspiracy theorism. There's not much harm in alleging a conspiracy to conceal the flat Earth. Even if you believe it's true, your daily life isn't going to be much harmed by that belief. If for no other reason than you're likely to ignore the discrepancies wherever reality makes your life easier than the belief would.
On the other hand, alleging a conspiracy to conceal autism as a side effect of vaccines, and living according to that belief, can potentially cause a *lot* of harm.
---
So. What's the harm in magical thinking? It depends on the magic, and on the thinking, and on what you do with those two things together.
Bringing it back around to the OP, I suppose one could argue that the harm of thinking that human sacrifice improves engineering projects is that at some point in the future, after this belief has fallen out of favor, but the community is full of angry mobs looking for an excuse to lynch people, rumors of this thinking will get innocent people killed.
But I'm not sure how you'd put that to a tribal shaman.
"I know you believe this stuff, but in the future people won't."
"Gods forbid! Literally! I will sacrifice *extra*, entreating the gods to forbid any such future!"
"No, I mean, people won't believe it, but they'll get murdered by other people who will think they *do* believe it."
"This future sounds as stupid as it does senseless. I doubt the gods will ever permit these things to come to pass, but if they do, I pray I don't live to see it."
"Keep using that bridge and your prayers may yet be answered."