What specific regulation would have prevented this? Or is this just a knee jerk response against "deregulation"?

the one simple one I can think of would be to specifically make depositor acknowledge “hey this is not FDIC ensured, do you want to proceed?”

probably still some percentage of people would fall for it and continue with the creation of an account but at least then this discussion here would be “stupid is as stupid does.”

One could make a regulation that account data cannot be lumped.

Sounding edgy doesn't really mask the fact you have no idea what you're talking about. See https://en.wikipedia.org/wiki/Dodd%E2%80%93Frank_Wall_Street... for example