My favorite is that if you try to follow a safe distance, some jerk will immediately move to fill the space
So once you restore your following distance, that person has cost you less than 2 seconds.
Is it a bit annoying? Sure. But it's not a reason to start tailgating (not that you were necessarily claiming that).
The fact is, you can have only so much space in front of you as other cars allow. I had to reduce the distance literally because of this. It then stopped happening.