It does not absolve the other person from responsibility for not following the required safety protocol. The car in front of them might have had to brake for a perfectly legitimate reason.

I mean, suppose that the other driver was driving while drunk. They might have arrived to their destination safely without the asshole in front, but that's not an excuse against a DUI ticket.

Maintaining a safe configuration of cars on the road is the collective job of everyone who is driving on it; and conversely, it takes just one person to ruin it for everybody who is doing the right thing. So it really needs to be a part of the culture of driving for that to work. And we don't have that in US, unfortunately (though, to be fair, there are far worse places to drive in).