Apple has barely any market power in laptop/desktop. They can do whatever they want there, I don't care, and neither should the DOJ. I also don't think they're meaningfully leveraging their phone market power to increase their computers market power, but maybe I'm missing something ;needing an Apple computer to develop for Apple phones is maybe a concern, but doesn't strike me as rising to the level of anti-trust litigation.

On phones, in the US, they have a dominant position. US Anti-trust doesn't require a absolute monopoly; merely having a dominant position is enough to prohibit anti-competitve behaviors.