I'm not sure this is absolutely true. Years ago I installed an app on my iPhone (Now Playing, a movie times app). That app was removed from the store years ago

I'm not sure this is absolutely true. Years ago I installed an app on my iPhone (Now Playing, a movie times app). That app was removed from the store years ago by the author. Recently I bought an iPad and if I go to "purchased/not on this iPad" in the App Store on the iPad, the app still shows as available for download. You can't search and find it in the store though. Maybe it still shows because all my devices are iCloud backed up and I never removed it from my iPhone.