You didn't say but I presume you are talking about blitz ratings which is where you play most of your games.
Since everybody starts at a 1200 rating, it is possible that you encounter more true beginners whose rating is rapidly falling through the 700's on the way to whatever their true rating will be (at 500 or below) than those who have stabilized in that rating range.
Anyone else notice that the sub 700 rating players play a lot better than those higher. It seems like we have a lot of lurkers.
Playing against 700-800~ rating players, I've noticed they're more likely to make simple mistakes. Ie. Leaving a piece that's about to be captured undefended when there are ways to protect it.
The sub 700 rating players are not only more careful but also seem more likely to use advanced strategies. Anyhow, that's my expereince from setting my rating to play agianst those of all ratings.