The thing is that today you dont even need access to the coversation when you have metadata. Imagine, a woman calls a number of center for planned parenthood, is on the phone for 20 mins. Then she calls a number of her gyno doc for couple mins. Then her phone is located at that gyno doc a week later for 2 hours or whatever it takes. Do you need to decrypt the conversation? You already know what was discussed.
How sure can one be with proprietary apps that the users are in fact the only ones who can decrypt their messages?
The thing is that today you dont even need access to the coversation when you have metadata. Imagine, a woman calls a number of center for planned parenthood, is on the phone for 20 mins. Then she calls a number of her gyno doc for couple mins. Then her phone is located at that gyno doc a week later for 2 hours or whatever it takes. Do you need to decrypt the conversation? You already know what was discussed.