That's my point, Android can have more than one app store running yet people choose to use one primary app store. The nightmare scenario of having to run multiple app stores that the OP seems to be scared of is a non-issue on platforms with multiple app stores.

In Android you don’t even need an App Store to install an app. All you need is to find an apk and download it. And providing an apk is exactly what many vendors do.

Sure, but it also pours cold water on the idea of having alternative app stores in the first place.

I wouldn't say so. Let power users have their iPhone equivalent of F-Droid or Aurora Store if they care while most users will just use the default App Store. I personally download apps off the Play Store as a last resort if they don't work on the former two.