Earlier quoted context omitted.
If it was an open platform, then Apple couldn't charge any more than Steam which is on an open platform, because nobody would pay that much unless forced to. Wait, Steam charges more? Never mind.
Your "nobody" is doing all the work. Steam distributes to Windows, but you aren't required to use Steam to distribute to Windows, and then many people don't . Adobe isn't paying Valve to distribute their suite. Epic doesn't use it for Fortnite. Random enterprise software developers have nothing to do with it. It's like pointing to the existence of people who willingly buy a BMW as a justification for forcing everyone…
You buy Adobe from Adobe, "Get" Adobe from Apple, and log in with an email.
Also, a minority of consumers by headcount choose Apple. A majority of wallet share is spent by those who do choose it. That's behind most of the sour grapes.