Your question assumes that the DUL is actually a meaningful anti-spam mechanism. It is not.
Could you elaborate a bit on what you mean by "meaningful"? As someone who uses the DUL list as an anti-spam mechanism and who experiments with turning it off and on, I can definitely say that turning it on reduces the amount of spam I receive (on the order of about 100 messages a day).
I recognize that it also harms folks like you for many of the reasons you give. But I don't understand why you say it is not a meaningful anti-spam mechanism.
--Paul Hoffman, Director --Internet Mail Consortium
