What it does is make people realize that nearly everyone who drives, drives a little impaired sometimes. That stops us from thinking this is about "other" people who can be punished to an arbitrarily high degree. Instead, now we have to acknowledge that it will be our sons, daughters, spouses, uncles, and cousins. It's just a matter of whether they got pulled over after a restless night or trying to finish a school assignment or working too late thr night before.

So, go ahead and punish people for impaired driving. But punish them like you'd want your daughter, cousin, or yourself punished. Not like a criminal who has crossed a major moral line.