That's the exact point I'm making, fundamentally a large portion of these formats(PSD, JPG, PNG, MA, 3DS) can't be resolved.
If two people touch the same file at the same time someone is going to drop their work on the floor and that's a bad thing(tm). You need to synchronize their work with a locking mechanism that informs the user at the edit(not sync) point in the workflow.
This way you can look at both and resolve the conflict.