I think that we can all agree that it will be much more uncommon for someone to throw a round 100 points above their rating. Where from personal experience it is not that difficult at all to take a dump on a round that is 100pts below your rating .
As for all the ratings creep talk. I have to strongly disagree. My rating is the same as it was 10 years ago. That would mean my skill level has actually regressed over the last decade. On second thought...
Because ratings are based on who is in your pool, ratings aren't creeping as much in divisions that never play with the Open pool. If you play in Open pools all the time, you're rating will rise. Even if you aren't actually playing any better than if you had played in Am events. The more high rated players in your pool, the more likely it will affect your rating in a positive manner.