> Android has a plethora of app stores, there have always been tons of them.

Google put restrictions on Android so that third party app stores can't install in the background, auto-upgrade or batch install.

> Google Play Store won out on Android simply because the multitude of stores was a nightmare for customers.

The Play Store is the only app store on Android where users can install apps in the background, auto-upgrade apps or batch install apps.

The reason the Play Store won out on Android is because it the only app store that Google allows to have the features app stores require.