[PandawanFr]

The issue is other factors may force you to use an alternate store. My college uses Proctorio for online test-taking. I am required to use this for the class. The issue is, the extension is only available for Chrome (I've tried other Chromium browsers and those don't seem to work as well). As a Firefox user, I don't really like having to switch to Chrome just to use an app that I never wanted to use but am forced to.

The same could apply with app stores—if a company, school, or other requires that you use an app that is only available on a less privacy-friendly or perhaps more intrusive app store, that doesn't sound like an optional/risk-free alternative to me. Once you open the walls there's no going back.

[temac]

Maybe Apple could display a prominent warning that this may put your personal data at risk, if you choose to enable alternate stores, and remind that regularly (including during each boot, when using the apple store, etc.), giving leverage for users who actually do not want that to refuse forced installations by third parties.