A 12ga still has to hit important parts if it's going to stop someone.
The WalMart guy clearly didn't know what he was talking about but I think I'd rather have a raw beginner defend themselves with an AR than a 12ga.
A gun guy might not think "2 3/4" bird" has much recoil but most all "non-gun" people would vehemently disagree.
Does it have to be a $900 gun? No, but I'd rather it was an AR than a 12ga. I'd rather it was almost any long gun than a 12ga.
Still happily answering to the call-sign Peetza.
The problem, as you so eloquently put it, is choice.
He is no fool who gives what he can not keep to gain what he can not lose.
-Jim Eliott, paraphrasing Philip Henry.