[amanda99]

I'm sure the ad networks do a lot more than use high precision variables for soft-linking.

These are professional networks with a ton of capital thrown behind them. They have pretty decent algorithms, heuristics, etc; and you don't make money (compared to the other data correlation teams) if you do simple dumb stuff. I'm certain they take into account those trying to be privacy-conscious, if only to increase their match rates to be competitive.