If I have an ebook store and want to give iOS users a nice experience when buying books Apple will make the books more expensive with 30% and on top of that if I want to give my users information that they have the option to buy cheaper from my website I can't , Apple is preventing their users to get informed/educated on how to get cheaper stuff because this information costs Apple money.
Btw you can have apps that do not use any of Apple SDKs (for example engines will use the OS core and neither of the fancy GUI toolkits and languages)
Btw you can have apps that do not use any of Apple SDKs (for example engines will use the OS core and neither of the fancy GUI toolkits and languages)