I install syncthing on ~all my devices and haven't yet touched rsync. Some reasons I prefer it:
1. It's automatic (sure, scripting regular rsync syncs probably isn't hard, but...)
2. It's p2p across all my devices (which from what I understand is not how rsync operates)
So as long as my laptop and my desktop are both turned on I can trust they're always fully up-to-sync with each other, and in my experience they always are.
as a personal syncthing user, i get it. although its clients in non-linux os can be better, especially on ios.
on the other hand, the accompanying video did mention rsync and a future video on syncthing, which might shed some more light on this decision.