It's less about them being stupid and more about us not knowing more about them. If you dropped me into Africa, or even NYC, I'd probably not be equipped to survive long on my own.
Guineas don't like change, for good reason. Unlike us, they have monovision, so they kind of rely on things being where they always are. If you move their water dispenser every day, you'll have frustrated birds.
They can't see in the dark, so once the sun sets, they're stuck wherever they are until it comes back up, unless we leave a light on.
They weren't meant to be where it's cold and wet. Adults do ok, but if they've keets tagging along through wet grass or chilly mornings, odds are some will succumb.
There's not a lot of info for us to read to learn about them, so learning comes mainly from watching. I've learned a lot just quietly sitting with them while they free range and in the coop when they're broody. Just remember, if you walk through your house and someone has moved your furniture around, you'd be confused too, and that's assuming you don't have monovision.