#3 Dressing room disharmony
Mauro Icardi's history with Maxi Lopez is well-known public knowledge. This has brought him unwarranted attention from the Argentine media and his countrymen.
There have been a lot of negative comments about him in the press and any team which wants to maintain it's harmony would steer away from. Maradona is a footballing god in Argentina and this is how harsh he has been on Icardi.
"Higuain is ten times better than Icardi, [Icardi] doesn’t know anything. what he does know is to go to his friend’s house and ‘eat out’."
“[Icardi] knows how to (have sex with his friends wife). He does that very well. He can find his friend's house easily. He doesn’t need a GPS for that. That’s why Higuain has to have another chance.”
Comments of such nature have been a common practice.
Additionally, his spat with Inter's ultras is another feather in his cap which has further consolidated his public image of a trouble-maker.
Thus, to keep the team's dressing room harmony intact and divert some pressure away from them, it was in best interest of the team that Sampaoli reduced him to the role of a reserve player.