I mean, true...but I don't think the average user is paying for the service rather than they're paying for not having to worry about setting up everything needed to get syncthing working.

I don't consider myself a luddite in any way, but within five seconds of reading syncthing's install instructions even I basically just said, "yeah...no." And I say that AS a nearly 12 year semi-advanced linux user. It's not that it's difficult. But difficult enough to not be worth it for the average person.