Other than Zach, I don't recall anyone saying that Dybala absolutely can't play CAM or on the wing. He definitely can... What remains to be seen is how effective he is in the position. He's been a bit unlucky with hitting the woodwork and been rather poor with his finishing recently, and still put up good numbers, but he seems to have trouble moving off ball as a CAM so far and hasn't been great at finding space to receive the ball... so he's not touching the ball enough IMO, but he is showing improvement.
Regardless, sacrificing a little bit of Dybala to make the team work so much better (same deal with Mandzukic) is a no-brainer, and hopefully he will continue to grow into the position.