I still don't see anything saying that you must offer subscription sign-up through your app. IE.. Netflix. You sign up somewhere else, then access your content in app. You pay Apple nothing.
If you do not want to pay Apple 30% to recruit customers for you then simply do not offer the ability to sign up with-in your app. Problem solved. Quite belly aching pointlessly.
Anyway, small internet merchants without established credit card history do not pay 2.5 %. They pay 20%, + plus 50% of each sale goes in escrow for 6 months. Ask me how I know... I've been with a few start-ups.
[P.S. If Apple was trying to force all subscription services to allow sign up in iOS, (such as Netflix,) then that would be totally different and I would be totally against it.]