But that won't work for Epic, or for any competitor. Epic wants access to every iPhone customer, not just the ones who paid extra to add third party app stores. Heck, you don't even have to pay extra to sideload apps on Android, but they still lost a ton of people when Google kicked them out of the Play Store.
My technically-savvy associates, I suggest an Android to (especially if they want to dabble in mobile development themselves). For my family that just wants a phone that works, I suggest iPhone. The ecosystem tends to have a single right way to do any given task, which is a boon when they just want it to work without having to think about details.
If other people want to have unlocked iPhones, due to Apple's behavior being illegally anti-competitive, then thats OK.
Yes, they won important victories against the cellular carriers -- victories that we all continue to benefit from -- but let's not kid ourselves regarding why they fought those battles in the first place. They didn't just set out to defeat the incumbent gatekeepers, they set out to become them.
With just a tiny bit of imagination I'm sure we can come up with something which will work. Here's an idea: Let Apple sell Apple-locked and unlocked iPhones. It can work just like carrier locking. Buy one unlocked, maybe pay a little extra, and you can have 3rd party app stores.
That took me a minute to come up with. I am absolutely positive that there are many other degrees of options between full-control by Apple and full-control by End-user.
I get it though... people who like Apple aren't very appreciative of having options.