Yes, they are called conspiracy theories. I don’t know if there is a more specific name, but I don’t think calling it a fallacy is correct as a fallacy means incorrect, while a conspiracy means it is unprovable/secret. Conspiracies can be false, but they can also be true with proper evidence and then it is called a scandal.
> but I don’t think calling it a fallacy is correct as a fallacy means incorrect
The (logical) fallacy is in the word "must". Let's look at the statement again:
> if an aspect of a system benefits a group, that the group must have planned said system aspect
This is incorrect because sometimes groups benefit from things they haven't planned. If the statement were changed to "that there is a good chance the group planned said system aspect", it would no longer be a fallacy.
It's the same as the slippery slope fallacy. Slippery slopes are real things. Sometimes A does get out of hand and cause B. Saying that if A happens, B must happen is where it becomes a fallacy. Changing this to "If A happens, there's a good chance it will snowball and B will happen" also removes this fallacy.
