If you tell the average user they need to sideload your app to access some free content, they will happily click past any number of scary warnings. I personally would appreciate being able to sideload, but there’s a reason iPhones don’t get laden with crapware in the hands of someone inexperienced with tech the way that desktop computers do. Does that mean we shouldn’t support sideloading? No idea. But there are trade offs.

It is as soon as several must-have apps (say, the ones all your friends and family use to communicate) are side-load only. If they allow other channels to install apps and make them easy enough that non-nerds can do it, network effects will quickly make it de facto necessary to run at least some apps from outside the app store.

iPhone users pay a premium to have a third party evaluate apps before they’re out on the App Store. If they wanted to do the evaluation themselves, they wouldn’t pay that premium.