I do, and I'm not convinced either; if the drunk's doing a steady 70, it won't hurt me to do 55 in the right lane for long enough so he's well ahead of me and I have time to react to whatever stupidity he perpetrates next. Too, when I'm driving, most of my attention is focused ahead, so dropping back puts him squarely in the region where I'm most likely to spot him doing something dangerous in time to avoid it.

Contrariwise, if I speed up and pass him, I have to keep worrying about him. What if he decides 70 just isn't fast enough? He's both more willing to drive fast, and willing to drive faster, than I am, so if I make it about who can stay ahead of whom, I lose. But I, being neither drunk nor proud, am both more willing to drive slowly, and willing to drive more slowly, than he is. So I make it about who can stay behind whom, and I win.

(None of this, I hasten to note, is intended in support of mandated governors on cars, nor should it be taken as such; I've seen enough to know that trying to make something foolproof results only in a lot of annoyance and a better fool. But it makes anyone a better driver, and safer to be around, to understand that faster doesn't always equal better.)