It goes all the way back to the Deron Williams/CP debate before the 2005 draft. The Jazz chose Williams (despite the media saying CP was better) and there was a rivalry between the two, especially in the early years. The media loved CP and it bugged Jazz fans even though Williams outplayed him head to head. Thrown in his incessant whining and flopping and he is an easy target, especially when he was teamed up with Harden.
Lastly, go read the posts about the Jazz from some of the Suns fans on here. They didn’t help your cause. Mostly, some Jazz fans are just ticked the Jazz didn’t make it past the Clippers. We want everyone else to feel our misery.