I have an iPhone simply to facetime with my parents, who refuse to talk to anyone with a green bubble. You can't make this up. If I could use iMessage on any other device, I wouldn't have an iPhone. Apple knows this, and it probably scares the shit out of them.

What I don't understand is why so many devs choose to accept Apple's rules. These devs know full well that they will likely be f***** over like this in the end. Yet they still give Apple their business.

Much higher rate of sales (apps and IAP) and subscriptions than Android. Not sure how the ad market looks (I've not worked on ad-supported apps) but wouldn't be surprised if those—at least in some categories—also pay so much higher that they're more lucrative on iOS, too, despite the smaller user-base.

Because people use iOS devices, and they want these apps.

I think I largely understand the implications of the garden I chose, and I doubt there will be much anguish among my less technical family/friends about their loss when they fully grasp that they will never be able to run a DOS emulator on their iPhones.

The only reason we're talking about something as obscure as DOS is because it wasn't threatening. Now that people have raised awareness of the inconstency they're blocking it, like many other general purpose emulators.