This debate never includes how other teams draft, too. And it always has to stop short of college free agency as if those players weren't acquired via the same evaluation process, or else it doesn't hold up to scrutiny.
The reality is, we've done a better job than most teams by a long shot at the top of the draft. We've filled holes via VFA, and then done a good job in college free agency. Where we've fallen down is in the back rounds of the draft where the really good drafting teams excel. That's the difference between the Cowboys and the contenders right now. That also happens to be the hardest place to find good talent because you only get 3-4 picks, and the best talent is off the board.
CFA works for us because we've got cache, a history of playing those players, and because we can throw a bunch of guys at the wall and only have to hope that a few of them stick.