All these are because PD tried to copy-paste iRacing rating system but in a wrong way.
@Outspacer
Yes you are correct.
"There are two ways to move forward in your iRacing career. ‘Vertically’, so to say, you can move to a new series, which is enabled by a promotion to the next license class (there’s Rookie, D, C, B, and A). You can also stay within a series and progress ‘horizontally’, based on iRating".
All ratings are working within this logic:in order to give people fun/competitive and clean races.
So they use licenses,iRating and safety rating -plus divisions- (in official races).All are connected to each other.Its complicated compared to the GTS system but it make sense.PD tried a more "simple" version by just creating DR and SR ratings.DR for "pace" and SR for "safety".