By opting out sometimes you have to provide them with even more information than what they initially had.
I guess we're lucky that most of these SEO-saavy brokers seem to at least pay lip service to US/EU laws (or even do so voluntarily, since I think only a handful of states actually restrict selling your publicly-available or personal information online).
I shudder to think about what's floating around for sale on the dark web or companies hosted in countries that don't care about US law.
If this worked then anyone could opt out anyone else, which some people would object to. I think that's the loophole they use to force you to provide even more info.