Even a cynic like me wouldn't go so far as to assume bad intent here. Signal is open source so the file format should be readable and likely this is just an oversight, I guess it's not a highly requested feature. Have you filed an issue?
In the beginning, it might have been an oversight. Now moxie is just making seriously misleading arguments on behalf of people he doesn't know to make their service worse.
What are you referring to? An option to choose your backup location got added two years ago. It works on Android 10 and above.
https://github.com/signalapp/Signal-Android/commit/ee3d7a9a3...
This means:
* Backup must be automatic.
* Backup must be done off device.
* Backup must be common enough that messages aren't lost.
* Restore must be available to person of average technical ability.
* Restore must not require a person to remember typing in a 20+ character pregenerated number they probably lost in last 2 years of having Setup signal.
This is the bar other messaging apps have set.
It's also funny how demanding on use of phone numbers, shoving in crypto currency and demanding everyone to use out-of-date Electron app is somehow fine, but making backups user friendly is suddenly a massive "security" issue.
This is the BS security theater I despise at Signal. It's the software equivalent of having every single airplane passenger take off shoes.
Backing up to the same device on which are running out of space is an extremely obvious problem, to which the solution is to just ask the user where they want the backup stored instead of deciding for them.