[Russell Sobie]

It's based on the analysis of the game mechanics that benefit or discourage poor player behavior. I shall break it down:

If someone has little to no regard for the safety of themselves or others in a sim race, what is the most efficient use of their time in a sim race? Answer: be super aggressive at the very beginning, and IF YOU SURVIVE, keep racing. If you don't survive, simply leave the server and go about being a horrible human being outside of sim racing as soon as possible.

Given this premise, a careless driver will be incentivized to be as aggressive as possible the earlier in the race it is in general. If the result of this aggression is an immediate DNF, then they will care less about the amount of time they wasted in the race. The longer they survive the LESS an efficient use of their time it is to be dangerous to themselves and others. 

A side benefit of keeping damage percentages down is that if certain drivers are going to behave badly REGARDLESS of the damage percentage*, it is better to allow those they harm to continue racing if they so choose. And since the offender actually survives early incidents, they will at least be incentivized to continue the race and possibly learn a little race craft, instead of bailing immediately and going off to torture kittens and puppies in real life.

I am speaking strictly of car on car impacts. Drivers that simply don't have the skill to do 10 laps in a row without going into a wall is a totally different subject, in my mind.

*Different premise than I'm posing above. I actually think that careless asshole drivers don't think about their time efficiency at all, nor do they pay attention to damage percentage. This new premise is specifically to make sure that those that can put up with a few assholes punting them off the track will still get to keep racing for the next 19.5 minutes instead of getting a DNF because someone t-boned them T1 Lap1 through no fault of their own.