If I take photos on vacation and throw them in a sync'd folder the next time both devices are online they will resolve the new file delta between that shared folder. That doesn't imply I always need one or the other device online. The more devices syncing the less likely it is that only one would be online at a time, but again there's no requirement there for an always on device.

Anyway... SyncThing is fantastic for users who are willing to invest some time learning how the software works. Every paid for product seems to cater to the "it just works" mentality thereby sacrificing control to me, the user, to handle situations that can't be handled by overly simplified, cloud-first, lock the user into our licensing model solutions. And don't get me wrong, those are fine for many people. For users who want more control via more responsibility - then SyncThing is great. But I don't like how they are spreading FUD about it just to get some name association.