That Patreon is even considering keeping the app is proof of this.
Depending on how overt Patreon's app is about ringing the alarm bells (imagine a "JUST MAKE A SHORTCUT and save 30% on everything!!!" popup) would just get them banned too, no doubt. Presumably criticizing Apple is a bannable offense.
No, that Patreon is "even considering" keeping the app is evidence that they get more valuable information about users and their habits from the app than they could from a website.
If the experience in an app is form, graphs, and payments... use the website. It apparently saves that company 30% and, to your point, keeps your computing habits yours.
Facts are simple here: Apps grant easier access your habits and identity as compared to a relatively-sandboxed browser.