I've been playing the game a little while now, no where as long as some but it does get very annoying when you play a game with someone who quits because they are having a bad round and doesn't want to effect their ratings.
So far I have never not completed a round that I started.
I think that the rating system should take their round in to its calculations. We can all complete a round if it gets frozen, you just have to finish it on your own.
If someone quits a round then I think that their current average score should be used for the remainder of the holes. For example if someone is 4 over after 4 then they should be calculated at 9 over for the 9 holes.
Perhaps that might stop people from quitting and finishing the round like we would do on a proper course.