And if I access Patreon via Chrome on Windows, and use Chrome on Windows to consume the artist's content, clearly I prefer the Chrome and Windows experience, so Microsoft and Google should be getting their 30% cut, right?

... and of course the user found the artist elsewhere than the iOS app store. They found them on youtube, or reddit, or _possibly_ on the webview inside the patreon iOS app, which is also _not_ apple's App Store content, it's content provided by Patreon.

Again, should accessing my bank via the Safari or Chrome iOS app mean apple gets 30% of all my bank transactions, just because they were displayed on a webview inside an iOS app?

The logical conclusion is that if you buy an Apple device from www.apple.com on your Windows PC, Microsoft should get a 30% cut of that sale.