It's a response bias. People who are smart, have good stats, and care about their application likely put more effort into their app so their app is then more competitive. Those same people are likely to find themselves in places like grad cafe shootin the bull and hypothesizing about sysplus updates; so I would surmise that we are not reprepsentative of the entire population.
Mech.Eng here, well respected engineering school. 167Q, 3.7GPA, several publications in grad school, a patent, strong letters. Last update 12/24. Will be very disappointed if I didn't even make past initial screening?