The two second rule is for clear dry days... nights, wet and grotty conditions look to double it.
It's one of those things that good drivers observe and muppets who can't see or plan 10 feet beyond their headlights cock up for you.
At least if you maintain the gap, even if you are overtaken, not only are you able to react safely, but the idiot who is travelling too close you your rsend has a bit more time to slow as you aren't on your brakes and there's a reduced chance of them shunting you..