Perhaps 100% of spammers hide their registration data when possible,
but I wouldn't say that 100% of hidden registrations are spammers.
An RBL option of this type of data would probably mean forced
elimination of a benefit to the public - privacy.
There has to be a balance between expectations to privacy when participating in a public space (the internet). Putting your name and address behind a domain is not unreasonable in my mind. You are afterall publishing DNS info, so its not a case of total privacy.
I use RBLs to score messages, not reject them.