Valid points, but they pose additional risk. I find you have no "safety net" in case you screw up. Next thing you know, you've fumbled or dropped either the wheel or the bike and then it's gotten scratched or dented on the concrete floor.

Also, considering that my bike has disc brakes, it's much easier to put it back together and line up the rotor properly when the wheel is vertically aligned in a stand.

I am still a newb. Maybe with more practice I will be comfortable taking the "training wheels" off and disassembling without the stand.