You can always use other software as well. The only reason HN believe Apple to be a monopoly is because the product they purchased does what it was advertised to do - security through chain of trust via an good-but-imperfect organization. It's only a legal monopoly if the courts say so, and the judge in Epic v Apple defined the market in a way that actually made sense - they aren't a monopoly on mobile game purchases, but they did took anticompetitive actions in that market to stifle competition.

> I'd argue where there isn't a thriving marketplace of choice monopolies should have to have the same rules with all their partners.

They can't have a monopoly on iPhones because the iPhone isn't a market - it's a device where the App Store is the killer feature. There are other products you can buy that compete with the iPhone and its app store.