This kind of situation happens a lot nowadays and I don't blame the coach for the decision to leave out some players. It's his responsibility to make the team better and whatever approach and decision he makes is okay for me even though it will not be in favor of some players. Every coach has their playing pattern and they know the kind of players that can execute it perfectly for them so if a player is left out and they are feeling bad then they should go join another team. Garnacho might feel disappointed but every coach must do what must be done to make the team better. We saw how Enzo Maresca did the same thing at Chelsea and now they are better than before. As a player there will always be a coach that will like your style of play even if you're rejected by another.
I agree with you because Amorim needs to do his best to rebuild the Manchester United squad, and pandering to the egos of some players who are having problems with him will never solve the situation. The coach's decision can determine the club's path to improvement, and if players feel disadvantaged, they can take the step of joining another club. However, the situation is now complicated because several clubs interested in the services of these players have been unable to fulfill their requests due to Manchester United's high asking price, and their expectations may not be in line with those interested. Garnacho is in a difficult position, as his market value continues to decline, especially if he doesn't get any playing time next season.