Mathias Pogba was right.
The coach is the management tool, he is responsible (and paid) to ensure that there is no discipline or motivational problem in the squad.
If the players are spoiled, childish, lazy or angry, it's still his fault, with his leadership qualities he must be able to solve such problems that, more or less, exist in all teams.
Mourinho didn't do it, perhaps because he himself has become a little too comfortable after all years. It was also clear that he himself, not least through his behavior in the media, created problems.
So instead of being the management tool, he became a burden and the reason was his shortcomings as a leader.
Altogether his own fault.