> Furthermore, there's nothing stopping that app maker from bypassing the app store and simply making a webapp, so this argument that you need an iphone to open the door is really moot

The door opener uses NFC, and iOS does not allow webapps to use NFC, only app-store apps: https://caniuse.com/webnfc

Apple has consistently made the experience of using webapps worse, including making installing them so convoluted that most users continue to not even know they exist.