Why adding an additional, unnecessary, superficial requirement?

It's not necessary to provide the functionality and enforces the dependency onto he potentially hostile actor (case in point: Microsoft disabling email account of Chief Prosecutor of ICC because US requested so).

It stifles innovation in the future and hurts GrapheneOS right now.

Let me turn the question back at you: why do you think adding unnecessary dependency is better than not adding it?

Does it serve users, governments, service?

Does it anything good for the interested parties or does it only serve Apple, Goggle and the US government?