Wouldn't that be equivalent to making your work public domain, which isn't possible in some places because you're not allowed to discard the automatic copyright you get under the Berne Convention? I don't think that's any worse than no license at all, but it's not clear to me that it's any better. IANAL though.
I'm not sure. However, I think it might be enough to throw a monkey wrench in future claims of ownership. If I author something and declare it 'not copyrighted', at the very least it makes the case for claims of ownership a bit less solid. In some sense 'public domain' declarations seem to be a type of surrender to a perverted system. TBH I've read some copyleft attributions and been nothing but confused.Wouldn't that be equivalent to making your work public domain, which isn't possible in some places because you're not allowed to discard the automatic copyright you get under the Berne Convention?