You are confusing market access and distribution. If I wanted alot of eyes on my app and I saw a benefit from the appstore then I would pay the 30%.

All I want is being able to give to MY customers, who I paid MY money to acquire, a native app. Apple is refusing to allow this, unless I pay protection money. Textbook rent seeking

Belated.

I can think of many exampled that have worked out. In some cases, apps like Gambling apps are not allowed to use the Play store at all, and yet manage to just fine and get installed directly as APKs.

It definitely varies business to business, and I'm not saying that I wouldn't put my app on Google/Apple, but that is because I do need the discovery.

In the case of Basecamp, they bring their own customers and network. This is true of a lot of big companies and Enterprise apps (some of which have exceptions already).