I want auto updates for my games so close to “always” that you can only tell it’s not 100% if you squint a bit. I use Syncthing in other contexts, like syncing emulator saves to and from desktop and Steam Deck, and it’s not quite as easy as Steam cloud saves.
Setup is annoying, and feedback on whether or not it’s working is a bit rough. I’ve lost data by misconfiguring it before. You have to run a background daemon on a device where battery life matters, so I tend to shut it off when I’m done. Syncing saves with SyncThing requires knowing where those save files are, whereas being built into the launcher client means they already know where those saves are, and that step is already done.