Yeah, but you can be charged with a dui for having, like, two beers.
Do you drink? Do you feel buzzed after two beers?
Meanwhile, there's old-ass people that barely have reaction times and people that are as dumb as they come able to operate a multi-ton vehicle on the road. Let's not forget the underinsured assholes with bald tires, or people that are too distracted to drive. There's also folks that can't handle driving/general logic allowed to operate what amounts to a murder machine in the wrong hands.
I'm not saying getting hammered and driving is a good idea, just that MADD has pushed the envelope a bit far and for every person driving home after a beer, there are hundreds more dangerous drivers commuting on the road each day.