Receivers drop "catchable" passes and quarterbacks make "bad" throws on every team, Dallas/Dak is no exception. Many times it comes down to a crucial drop, or a spectacular catch or throw to win games. Would Dallas have lost to Seattle if the snap to Romo wasn't bad? Would the Steelers have won the SB if Ward hadn't make the fantastic catch of a horrible pass and managed to toe tap after the catch? What if Carroll had run Beast Mode instead of trying a risky pass into the teeth of the defense? What if Walls had played Clark instead of peeking at the quarterback?
Dak attempted 596 passes last year, if he had thrown a few more passes better or the receivers had not dropped quite so many, would that really have brought this team to the SB?
Neither the drops or the bad passes were the reason this team didn't win the SB, it just wasn't good enough. If making the playoffs or winning the division is all that someone cares about, then the drops/bad passes probably could have gotten the Cowboys to that point, but all that would do was result in a worse draft position, you play the game to win it all, division titles and playoff games are just nice stats to brag on. Dallas has the highest winning percentage of ANY team, ever. That's nice, but the Pats and Steelers have 6 SB wins, we have 5, that's what matters.
You can blame Dak all you want, but I seriously doubt if they'd had Mahomes they'd have won the SB...