Unpopular opinion: This was a no brainer. Apple wanted 30% (or was it less for subscriptions?) on any business that used apps, no matter if they used apple infrastructure or not. Just think about it: one company is in practice entitled to 30% of what any other business makes (in any industry)!! Also, I think apple brought this to themselves by picking a fight with Spotify (on Watch support).
I think argument about 30% is not that good. There is a number of services that Apple provides like software distribution, updates distribution, reviews (even though they don't benefit software creator directly, they build trust in the platform and attract more users), invoicing, regardless on the location (this one is really big - getting a single invoice from Apple instead of dealing with potentially thousands of d…
If you are an iOS developer and and 2 other stores would exists, then you would publish on all to maximize your profit, and hard core Apple fans still get their app from the Apple store but it could cost a bit more.