Syncthing is awesome. I'm never losing data to a damaged or stolen device again, and it makes accessing data from a computer and sending data to the phone so much easier.
But we have to keep in mind that syncthing doesn't protect by default us from accidental deletion, so it's not a 100% replacement for a backup.
The truth that is hard to swallow...
We are techy people who enjoy the concept of the fediverse, but the general public will never use it if it doesn't become simple and straightforward.