This makes some sense, but it occurs to me that a blind person has no way to distinguish between an image that has no alt tag because it would be meaningless, a

This makes some sense, but it occurs to me that a blind person has no way to distinguish between an image that has no alt tag because it would be meaningless, and an important image that the author simply didn't think to write an alt tag for. alt="(Decoration)" would clear it right up and only takes a few seconds.