Question about anti static wrist band and preventing static while embling brand new computer parts?

The logic behind this is that when the power supply is plugged in, with the a-s strap attached to the power supply frame, you would be directly connected to your house's (or whatever building's) ground via the breaker panel. So if you're not going to have the power supply plugged in while you're doing your thing, then there is no advantage to following that instruction. I have installed memory modules and various other components many times, but always with the unit plugged in. You really should install the power supply first, and plug it in, just to be on the safe side.