I think this is a case of people using bidirectional file sync wrong. The point is to make the most up to date version of a file available across multiple devices, not to act as a backup or for collaboration between multiple users.

It works perfectly fine as long as you keep how it works in mind, and probably most importantly don't have multiple users working directly on the same file at once.

I've been using these systems for over a decade at this point and never had a problem. And if I ever do have one, my real backup solution has me covered.