I think what you and others are confused by is that you will be required to have many specific apps regardless of whether the protocols are “open” as you do now

I think what you and others are confused by is that you will be required to have many specific apps regardless of whether the protocols are “open” as you do now because the companies building the apps will always build proprietary features to get you to use their specific app, otherwise we would just coalesce around one messaging app and most will lose a lot of the money they are currently making. There is nothing stopping anyone from using open protocols or different messaging apps today. What’s so frustrating about Google’s attempt to leverage lobbyists to handicap Apple is that customers did coalesce around an app: iMessage, and all of this talk about “open protocols” is just marketing. The protocols you want to use are already here and already open!