I suspect developers are looking for these workaround because of the 30%. If Apple had asked for, say, 10%, would there be as many developers looking for loopholes?
I don't know. Apple perhaps should ask for compensation for "vouching for" the developer's app, hosting the app, distributing the app. But Steam shows us another model where the developer themselves pay a modest up-front cost to have their app hosted ($100) and then Steam steps out of the way.
I wonder if this would go a long way too to thinning the herd so to speak from the Apple App Store—perhaps improve the overall quality of the apps submitted.