Signal's threat model is that everything around you is hostile to you, except the parties you interact with. You are an undercover rebel in a totalitarian sect which would sacrifice you to Cthulhu if they see your chat history. Losing it is much better than disclosing it.
Your threat model is likely random black hat hackers who would try to get into your communication channels and dig some dirt to blackmail you, or to impersonate you to scam your grandmother out of several thousand dollars. Signal protects quite well against it. But the chance of this happening even in an unencrypted channel is low enough. You don't mind making the security posture somehow weaker, but preserve the possibility to restore your chat history if your secure device is lost or destroyed.
I suppose the problem could be solved by an encrypted backup with a long key which you keep on a piece of paper in your wallet, and / or in a bank in a safe deposit box. Ideally it would be in the format that the `age` utility supports.
But there is no way around that paper with the long code. If this code is stored on your device, and can be copied, it will be copied by some exploit. No matter how inconspicuous a backdoor you are making, somebody will find it and sneak into it. Should it happen in a publicized case, the public opinion will be "XYZ is insecure, run away from it!".
Yeah... We really need some key-management hardware where the secrets can be copied by some channel that is not the primary one. This used to be more common, before the IT companies started pushing everything into the cloud.
I have recently started to see computer boards with write protection for the UEFI data, what is a related thing that also did go away because mostly of Microsoft. So, maybe things are changing back.
I don't know. Now async I/O is all the rage and that is the same idea.