It's not that it's a hard rule to grasp. I'm pretty sure everyone here is aware that if you leave more than two car lengths distance in front of you, before you know it you'll have just one car length in front of you because someone trying to win the race sees an opening and jumps into the space. So you drop back to open the space, and ba-bam, another clever person jumps into THAT space. And so on and so on.

The only way you're going to get anywhere near that kind of space is to just give it all up and putter along in the slow lane, and even then, you're going to get beeped at from behind and cut off in front.