I appreciate Signal and that the Signal developers provide a very useful service to the community for free.

I also know a large number of people who won't use it because it locks your messages up in its own walled garden. People use apps like this precisely because they want to have control over their own communications without any third parties interfering! I have never understood what kind of threat model they think they're protecting against by not letting people take their own backups and store them according to their own preferences. Whatever the reasons it is clearly a deterrent to wider adoption.

This announcement might seem like progress but I doubt it will convince any of the people I know who won't use it because at the end of the day it's still a walled garden. If and when the promise of the comments near the end of the announcement is realised and we can back up our own messages and media freely from our own devices to our own (presumably also secure) backup facilities then it will be much more interesting.