Why would a player be better at MTT than STT?

[flyingmoose]

Given the same skill advantage in both formats, a winning player should win more per tournament at MTTs than STTs.

Tournaments are about finding edges and you'll find more edges over the course of several hours against dozens of fish than you will in one hour versus just a handful of them. Consequently, if you're a winning player you'll win more per MTT than STT, on average.