You have users who has iphones, and those users want you to develop an app. They can't switch phones. Buying a new phone is expensive. They use apps that only currently exist in iphone. There is sunk costs. Their social circle require them to use iphone. The phone was provided by the job and they can't use something else.

Should the developer spit in the face of those users and refuse to develop the app? No. They might not like apple. Might not support what apple is doing. The app might be horrible crippled and overpriced. Sadly the choice will still likely be to develop an app for the iphone because the small signal it would send to apple is microscopic compared to the major harm to your users.

Linus tech tips had a nice discussion around.