Homes are private property, roads are public property. So there is a difference.
It is allowed in my state (TN) and I have been stopped, I drink, but at home PERIOD.
Working off and on in the ER (when L&D is slow) I see the effects of drinking and driving quite frequently. If it cuts down on the deaths of innocent people, (you do know that it is usually the person(s) in the other car who have not been drinking are the ones injured/dead rather than the drunk, don't you?), then I am all for it.