Because the platform only exists because somebody created it, somebody specific not some consortium.
I don't want my iPhone OS to be created by a consortium, I want it to be run by Apple...
If that consortium is so great, why don’t they just make their own product. Let the public decide what they want.
That would be theft. I am honestly amazed that people are still in favor of gross government overreach in the era of Trump.
The pre-edited version of the original post asked the ludicrous question "So now we’re going to have governments design the software in our phones", so he got a ludicrous answer in kind. But in theory, if Apple's control of the App Store platform constitutes a monopoly, it would not be gross government overreach to pursue antitrust, as it has done historically, even if it has been unfashionable in recent decades.
But it's not a monopoly. The vast majority of the "app store" ecosystem is the Play Store. Apple's "App Store" is a minority player.
Otherwise you could arbitrarily divide any platform recursively until something is a monopoly in need of getting regulated.