The Patreon website is equally shitty, at least it was when I last used it last year. Haven't tried the app though. So you hands should remain toasty.
But I do agree, why not just send Apple a big "fuck you" and create a really good mobile website?
Apple is still really pushing it with the 30%. I do agree that they should get cut, or straight up charge app developers a yearly fee for being in the App Store (which they already do with the developer licens), perhaps a smaller fee per update and a fee for using their subscriptions feature (which I do like as a consumer).
Patreon need to tread really carefully, because what Apple does not that different from Patreons own business model. Creators are similarly complaining about Patreons fees.
Still 30% is a lot, but I don't know what the actual cost of running the App Store is.
You bought into the platform, so you have to pay by their rules.