Then in turn downstream users can legitimately obtain it without knowing that you're attempting to disclaim liability.
Consider some libfoo, and in libfoo you include example.mylang as a "quickstart" for the common use case, and many people use this as a starting point, modifying it a bit to suit their needs but not much. Technically you should attribute this file/function/class too, but in practice no one does, and no one really cares either.
I've had people ask me to put a license on 2-line Stack Overflow licenses (it's already CC-BY, but people still ask for some reason, I guess to comply with company legal dept.)
It's useful for stuff like that: you typically don't really care what someone does with your fairly simple examples/demos/etc. (which may not even meet the threshold of originality to apply for copyright protection) and whether they attribute it.
Whether something like this is even copyrightable is questionable. But releasing it under a license like MIT-0 removes any ambiguity -- whether it's copyrightable or not, the original author is allowing you to use it for anything at all, no strings attached.