> The only reason I can think of it's that it's deep state control.

Then you lack imagination :-). Let me give one example: "I am a fundamentally good guy, and I want to protect the people. If I was given access to all the communications of everybody, it would be easier for me to do my job and to improve the security for everybody".

Of course, (as you know) this is flawed, be it just because you can't guarantee that a surveillance system will only ever be used by fundamentally good guys in the eyes of their people. Or said differently, if you create a backdoor for the good guys, you also create a backdoor for the bad guys.

But it's easy to be well-intentioned and not understand that it's impossible to build cryptography only for the good guys. No need to invent a deep state when the simplest explanation is "the people who believe it are uninformed".