It's not a myth, more like a modern thing. Mourinho pre-Real Madrid was a great man manager. He knew how to get his team to go for a kill all for him and him alone. He was attacking the press, the referees, the opposition managers and the media but never attacked his players which led to the "us vs them" mentality. He made it as if it was the entire world conspiring on him and his players, which helped create the perfect mentality for the success.
The issues with Iker, Ramos and Ronaldo hit him hard I believe and when the players turned on him at Chelsea in his 2nd stint that's when the "us vs them" mentality his teams used to have turned into "me vs everyone else" for Mourinho. I think he became insecure. He never recovered from that Chelsea debacle. He now always had the feeling the players will turn on him at any moment like what happened so that's why he turns on them before.
He used to blame the referees or the media after every loss but now he blames the players several times for not following his instructions. He keeps on saying he told them to do this and this and the media should have recorded what he said in the dressing room to understand how he read the game perfectly but the players couldn't follow up..etc. This screams insecurity. Like he's not confident in his own abilities anymore so resorts to defend himself in public while blaming the players for not following his instructions. The old Mourinho was never like this.
I always think it's quite sad most of the new generation will only see the current Mourinho, the insecure, unconfident and miserable person who doesn't seem to enjoy the sport anymore and always has a feeling he'll get stabbed in the back by his team or his board at any moment. Many don't remember the charismatic, charming manager who was oozing confidence and personality, the manager whose players cried whenever he left their club to manage somewhere else because they were willing to die on the pitch for his own sake. This Mourinho was hit by Real Madrid and killed completely by Chelsea. Now he's just a shell of a man. From time to time he can produce a performance that's reminiscent from the past but never consistently enough.