I agree with this, but I have been using SyncThing for all three. Overall it’s served my friend and I well, despite the fact we’re both totally new to using it, and he’s very new to GNU/Linux and P2P software (other than torrents of course 
). There are a few gotchas that my friend and I have discovered, for example my friend didn’t realize at first that deleting his copy of synced files also deleted my copy But there are a few ways this could be addressed with UI changes.
Easier
Add some UI elements that:
- allow the user to distinguish between their own devices and other people’s, giving other people’s devices less permissions by default (eg ability to sync an update to a file but not a deletion)
- when creating new folder shares, asking the user what their intention is for it (eg keep folders in sync, move files from one device to another, send a copy of files to another device), and guide them through making sure the folders settings reflect that intention
Harder
Develop separate UI for syncing, file-sharing, and backups, using the same ST backend, and the same set of underlying device relationships.