The threat of DR loss isn't going to stop them, yet DR penalties ruin the system. Not a fair trade!!
The only way to implement a DR loss in a way that's reasonable to the system is by position penalty at the end of the race. (I'm assuming for now that a disqualification counts the same as DNF did before, so that's OK). But for that, the system would need to apportion blame, which frankly it is crap at.
What isn't OK is taking points out of an Elo-based system, especially since there's no way to gain points except from other player's points. But start down that road and it isn't an Elo-based system any more, it's something else (which might be fine, but I wouldn't trust PD to design it!).
But also I firmly believe the two ratings should measure two different, separate, things, and just do the best they can at those. (Note that #1 in my post pretends to the user that they have been docked DR, and probably affects matchmaking as well). Then the matchmaking has the best information possible available to it.
Note that the key point of my post is that SR is the rating that needs most attention, since that 99 SR thing is a real problem.
@Mr616 also.
Aren't you violently agreeing with me there? My points #3 and #6 basically say do away with fault and therefore do away with time penalties for collisions.
And I'm not saying nothing extra gets tacked on later, but first the SR has to have a solid core way of working. That is vital.