It's also intuitive if you think about error in self assessment. Skill is asymptotic to some upper bound. The closer to the asymptote (higher skill), then most

It's also intuitive if you think about error in self assessment. Skill is asymptotic to some upper bound. The closer to the asymptote (higher skill), then most likely the error in estimation is under it, since it cannot be above it. Conversely it cannot also be under zero, so error is most likely going to be above the actual skill line (over estimation, since it's clamped below it).