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It's also funny how demanding on use of phone numbers, shoving in crypto currency and demanding everyone to use out-of-date Electron app is somehow fine, but making backups user friendly is suddenly a massive "security" issue.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.