Messi and Neymar are not the problems of Psg, it's just that the club and other players expected too much from them and when they failed to perform or deliver they go angry immediately.
They are parts of a club so they share responsibility with other players and other people in the club for the club success or failure. However, if blaming everything and all responsibilities on one or two star players, it is unfair.
First why the club board members decided to buy those players?
Second why the coach decided to use a very attacking-skewed squad that makes their defense weaker and more vulnerable to counter attacks?
Lastly did they make enough support to their team mates and did they get enough support from their team mates in return?
Player performances also are affected by support or protest of their fans. In PSG, latest seasons we can see their fans have very hatred attitude towards their star players. How can their star players play best with bad mood?
Magical Mbappe he has now scored three goals in the last three game he has played he has such a big influence in the club.
Also last session Psg lacked a good coach Luis Enrique has come to improve on the squad and for the squad to work as a squad not put expectations on a particular player to deliver. Psg has the coach now, they need sign important players now to win the Champions League.
PSG just returned to winning in Ligue 1 that is not a good indicator for success of a coach in PSG. They want Champions League and hire Luis Enrique to win Champions League. They will wait for performance of their players and Enrique in Champions League and we should wait for it too.
The coach is experienced in Champions League as a player in the past and as a coach with Barcelona but he is assigned a big task in PSG. They have some big losses in this summer, Neymar and Messi left, and seems to rely on Mbappe for scoring goals.