Earlier quoted context omitted.
How is this an actionable anti-trust issue? iMessage doesn't even register as a messaging platform in the minds of most users globally. In the US is it dwarfed by at least three other platforms. Globally, do any of the other top ten (Apple is nowhere near the top ten) messaging apps allow third parties to spoof their service? The purpose of anti-trust is to increase competition and prevent unlawful monopolies. Apple…
So "monopoly" as a single entity controlling a single market is a simplistic view of the issue at hand. Anti-trust is far broader than that, where any anticompetitive action can be subject to anti-trust lawsuits/regulatory action. So the legal argument would be that, because Apple allows for a single messaging app, and interacting with that app requires an iphone, they're effectively preventing messaging app competit…
That is weapons-grade horseshit. You can put WhatsApp, Facebook Messenger and Signal on your iPhone and message to your heart's content. (I know, because I've had the first two on my phone before and they did not get killed in their sleep by Apple's native messaging app).