I can look at note history once I catch the error/if I catch the error, sure.
I had one case where I provisioned the wrong source image on half a dozen servers because I'd previously overwritten one UUID with another. One string of 32 base-16 characters looks like another at a glance.
Edit: Also, note history has limitations. It's only captured every eight hours, right? So values entered and destroyed within an 8 hour interval are lost unless the user hasn't closed the note and is able to find it in local undo/redo.
On the whole, "locking" just seems like a helpful feature if there are a good number of users who are using part of Evernote for reference material, not only live docs. It might even make sense to allow Notes to inherit lock status from the Notebook level.