> This can have a big impact for end users. Imagine an authenticator app ending service to all their users in such a scheme and how you will be cut out from all your accounts by this. How many authenticator apps do you have to use in parallel to mitigate this risk of a single point of failure?

This right here is a big reason, apart from actual restorable backups, why I root my Android device. Sure it is not required nowadays but it does give a sense of control if thats the right word.

So many times I had to restore older copies of apps like Chess or even Yoga app. The older apps allowed a functionality (downloadable content for offline view) which was straightup removed in newer versions.

Same for Authenticator or any other app which does things locally.