You'd have to watch the full video to get his whole argument.
http://railsconf.blip.tv/file/2081411/
It starts roughly around minute 46.
His point was in relationship with stakeholders. Most people, when making up requirements, think about the Absolute Best Thing They Could Imagine. However, in reality, they'd be equally as satisfied by something that's much less fully featured, but also much faster to complete. In addition, simplicity also tends to have performance implications.
He uses a permission system as an example. He worked for two weeks on a Best Permissions Ever, and then said "let's go back to the drawing board." They managed to find a 90% solution that he could code in a day and a half, was much more performant, and they found out that that last 10% didn't even really matter.