Yeah, double-clicking that DMG and dragging the .app 30 pixels to the Applications shortcut is a lot of work.
>That's literally no different than side-loading your own apps.
Yup, clicking and dragging is the same as configuring a different machine to properly build and provision.
You're being purposely disingenuous.
Second: many, many sites host their own DMG downloads, with zero fake download buttons. I don't think searching for an app's website on Google is significantly harder than searching for an app in the App Store (also I'm not sure typing in search terms is "one click", but whatever). I'll admit that using the App Store is slightly less work to install stuff, and somewhat more secure.
But from a user standpoint (I use a Mac with one or two App Store apps and dozens of DMG-installer-based apps) it's not a huge difference. And from a developer standpoint, that's not worth 30% of my revenue.
There's no reason for Apple to offer that on their phones since it dilutes the customer experience. Anyone that would care about doing that can still do that via XCode by side-loading the apps.
Case in point - where's the competitor for the Mac App Store on macOS? There's not. Users have to do all the legwork themselves. That's literally no different than side-loading your own apps.