I've thought about this a lot and I think there's a reasonable hypothesis in evopsych (I know, I know...):
If you're making material mistakes that hurt the social group you're in, especially things that cost extra work for someone else to undo and redo correctly, then you could be identified as someone ripe for removal from the group. Ostracization means assigning taboo or outsider status to that person, either as a way to get them to shape up and earn back the trust they lost or to remove them entirely with little remorse.
It will seem even stupider once computers can convincingly do all the "intelligent" things better than us.
In fact, they can already seem smarter, even when they're not.
Maybe we can move on to prioritizing humans on other criteria -- like how nice they are to each other, how good they are at making nice art, or skiing an amazing line down a mountain, etc.
As soon as IQ becomes a measurable thing, populations that measure it will act in ways that increase it. Shocking, I know.