I assert it is trivial to not buy Apple products, easy to make alternatives to Apple products and easy to buy feature equivalent devices to Apple products. In lieu of this what is the problem? If the government has a problem why not say any code should be able to be run on any device? Honestly I’m curious - what’s the problem? There are android phones that are superior to iPhones and let you run anything you want. Wh…
Judging by your phrasing, your interpretation of antitrust stems from Robert Bork and has been the mainstream thought for a long time. Read The Antitrust Paradox by him to see how we got here and why the courts have acted how they have for the past 40 years.
The current chair of the FTC, Lina Khan, was actually an academic prior to working for the government and has a long paper trail of how she interprets the law. In short (and extremely oversimplified), it modernizes the Brandeis interpretation that bigness is bad for society in general, regardless of consumer pricing. EX: If Apple were a country its GDP would surpass the GDPs of all but four nations. They argue this is bad flat out.
Can't say it was the only cause, but Khan's paper, Amazon's Antitrust Paradox - note the reference to Bork's book - is partially what resparked a renewed interest in antitrust for the modern era if you want to check it out.