I was getting massive accordianing from 7-11 spots back (depending on the start), I can only imagine what people further back were getting because of this. The rules are meant to avoid people attempting to do this on purpose, you can't really blame someone for being in the middle of an accordian when the flag drops. It also goes the other way too where I've been caught in the middle of braking for an accordian and been jumped when the flag drops by people who were just physically carrying more speed behind me trying to catch up when the green came out.
You can however say that people need to be a LOT more gentle on the brakes/throttle when we're under safety car conditions. I was ignoring the rapidly changing pace of the guy in front (driving like a road car with the brakes/gas) before the safety car peeled off and it was a massive aid to the people behind me in the field. But in the interests of not falling away from the guy in front of me at the start I was forced to join the rapid accordian on the final S/F straight. If everyone applied these rather basic principles though right up to the green flag things would be loads fairer and cleaner during our starts and restarts.