Something you should keep in mind is that being a monopoly is not illegal, and it never has been. If you make a great widget and, through honest competition, corner that widget market, that’s perfectly legal.

What ISN’T legal is using your market power to engage in anti-competitive behavior. It’s not illegal for Apple to dominate the phone market. It is likely illegal for Apple to use its dominance of the phone market to prohibit competing app stores from being installed on their phones. That is Apple operating in two distinct businesses - a phone manufacturer and a software retailer. Apple is using its market dominance as a phone manufacturer to gain an unfair advantage as a software retailer.

This is a pretty damning violation of federal antitrust law.