It is fairly easy to assume that there are other routes to food than publishing apps in Apple's App Store. No one is guaranteed abundant income in general, never mind via some third-party business.
If a particular practice is acceptable for Apple, then it is presumptively okay for other software companies to do, too. And conversely, if everyone in the market for software-development labor wouldn't be allowed to do something, we shouldn't allow Apple to do it, either.
If a particular bit of conduct would be a poor idea if everyone were to do it, that's a pretty good idea it shouldn't be allowed at all.
