Some Apple users and Reddit accounts received an email of the Apple Vice President of Worldwide Marketing Phill Schiller about declining the request of Steam Link for iOS.
Apple explained that after another evaluation of the App Store review team in Steam Link, the app has some issues and numbers of guidelines have been violated such as the user generated content including a method for filtering, objectionable material, reporting offensive content and the ability to block abusive users, together with in-app purchase, content code, and etc. Schiller added that Valve will still continue their work and will help Steam for iOS and Apple TV without violating the guidelines of the company.
Schiller also said in his email that the App Store is for everyone to have the best experience and has clear guidelines for all developers that must be followed for the safety of the app, for all users and developers.