Monopolies are also legal. But it's not unusual for industries which are dominated by a small number of players (ie monopolies or oligopolies) to face additiona

Monopolies are also legal. But it's not unusual for industries which are dominated by a small number of players (ie monopolies or oligopolies) to face additional regulation or regulatory action aimed at preventing them from abusing that position, especially when the service provided is viewed as "essential" in some way. I don't think it's an unreasonable position to hold that the app stores should be subject to this type of regulatory oversight.