[StavrosK]

Steam isn't manufacturing computers. This is about Apple the computer manufacturer. It's unfair for them to lock their computers/phones down so people can't install software without Apple's permission.

The App Store is more or less a red herring here (relevant only to the 30% fee being too much).

[OnlyForF1]

Is it though? There's no legal precedent that would allow for software vendors to force device manufacturers to allow their software to be run on the manufacturer's hardware. Otherwise we'd see Android on iPhones, legally-mandated Facebook integration on everything, custom car firmware etc.