Curry was a good defender maybe 2 seasons ago when he was MVP for first time. Now? Hell no.
Harden, Lillard, Curry, Kyrie, IT, Westbrook more or less play same type of defense. That is the reality of PG position. You don't ask them to be the anchor of your defense. In past 20 years, you can maybe count a handful of point guards that played elite on both side of the ball (Payton, Kidd, CP3,.. then maybe Wall?)
Was anybody down on Nash for not playing defense? Was anybody down on Rose for not playing defense? Both won the MVP. Westbrook was just an OK defender like Kyrie is now. He also won an MVP. Harden almost won an MVP on two seperate seasons with playing little to no defense.
When (lack of) defense is your main argument for Kyrie, it just says to a lot of people that you don't have much ground on this discussion.