I think it's a mixture of:
A.) CoD fans have a real ego problem, and they'll blame everything and anything about why they aren't performing as well as they want to, the only exception is being their own skill. Which causes a ton of confirmation bias, and every example of an obvious cheater is used to as a example of how rampant they are. They when in all actuality, they're the aren't as common as people think.
B.) People really don't know how generous Aim Assist is, so they don't know how to discern aimnotting over someone knowing how to abuse RAA.
I've received hackusations multiple times, once even from my own teammates. Hackers aren't as big of a problem as people are willing to admit.