That's... literally what the author said.

    If your solution is not simple, it will not be correct or fast.

Correctness may be the end-goal. But correctness is absolute. So it is a bad performance indicator to set as the goal. Yes, we can track bugs. But the absence of open bugs is no guarantee for correctness.

I can never say "We are 5% more correct than last week. Keep up the good work!"

Simplicity is a much better goal for the day-to-day work. Because it can be tracked, measured and evaluated for every individual change.