We can draw analogy between any two things. An encrypted chat is not a letter in the mail or a call on the telephone. It is an entirely new thing. Backdooring such chats is not "bringing technology in line with existing laws" it is, very clearly, passing new laws, and creating new invasions of privacy. It must be justified anew. The justification for wiretapping was not that there was no way to fight crime without it. Otherwise, when the criminals became wise to it, and began to hold their conversations offline, there would have been a new law, requiring that all rooms be fitted with microphones that the police could tap into as necessary. No such law was passed. Instead, the justification for wiretapping was simply that, once police had identified some transmission as relating to the committing of a crime, they could obtain a warrant, and then tap into the communication. The physical capacity without any effort by uninvolved individuals was the entire justification. That capacity does not exist with encrypted chats. The analogy is therefore much closer to the "mandated microphones" described above. Everyone is being required to take action to reduce their own privacy, regardless of whether they are subject to a warrant.

What is most striking about our "mandated microphone" analogy is the utter futility of it. Criminals have no issue breaking the law, and hence have no issue outfitting a room with no microphones in which to carry out their dealings. The same is true of any law targeting encrypted chats.