I just want to point a few things out,
1)
There seem to be some people who think the requirement to drive clean is on just the driver behind/trying to pass. In motor racing, that is inaccurate. If you are "defending" in an inappropriate way or even just slower and driving "erratically", you are potentially the one at fault if an overtaking car hits you. Motor racing rules aren't the same as driving on public roads.
This webpage summarizes the rules quickly
http://ignition.my/2012/09/20/snf-guide-to-overtaking-rules/
Anyway, what I'm getting at is that I've seen plenty of examples of people I'm faster than who are deliberately driving in a dangerous way to make it difficult to overtake - this behavior is no better than those who try and dive bomb. Examples of this are weaving along a straight, diving across the track in the braking zone, crowding a passing car off track etc.
2) The goal of the SR (just like it was in iRacing) is to make pick up races with strangers bearable to do. In that goal they succeed. It's impractical to have a human steward monitoring every race and the cost of developing a deep AI for that purpose is prohibitive. So here we are with a simple algorithmic way of adjudicating racing incidents.
PD just ask everyone to avoid excessive contact, and provide SR ratings to all involved. Ultimately similar style drivers should end up in the same races. People who bump, crash and leave the track will be matched with those that do the same, those that are extremely cautious and will never attempt a pass for fear of SR degrade, will be matched with like minded "hot lappers".
Personally, I've found the races on GTS to be pretty clean - equivalent to the entry level races in iRacing and I suspect a lot more people are playing GTS right now.
3) Finally, perhaps we should all have a little bit of patience and understand that not everyone else on track is hellbent on destruction - much of what I've seen on GTS (which goes back to beta) isn't necessarily deliberate crashing, it's just red mist, over-optimism, inexperience or different driver ability arriving at the same bit of track.
People miss braking points, they go for a gap that disappears, maybe they're just faster and get their car to a bit of track you didn't know it could go. Not every contact in GTS is down to griefers. The system is working well - I have yet to see a car coming the wrong way down the start/finish straight or someone immediately swerve at the start to try and block the road. When the T1 accidents happen (and those are a fact of life in every series), the ghosting system helps avoid a massive pileup.
That's all the system was designed to do, make pick up racing playable - for that, it works as intended. If you want even "cleaner" racing, then join/create a user made league and then you can watch replays and hand out penalties in accordance with whatever rules you choose.