Because he intentionally sabotaged the 2019 season, crapped on his teammates and fans on the way out the door, and had to be slapped around in 2018 to get his head on straight then, too. All because he didn't have his precious new contract until "45".
He made his choice. He could have come to OTAs, met his new teammates like everyone else, and gone out with guns blazing, but he did the passive-aggressive selfish thing instead. Not a good look even for those who choose to look the other way on it.
He, and now his little pet protege, Erin Rodgers, are the only QBs in NFL history to skip OTAs. It's a jerk move.