I used a tool like this posted to HackerNews a couple years back (against my better judgement, eh), and the information on a few of the data brokers afterwards was not only not removed but actually showed a green checkmark ("verified").

It's entirely possible the data brokers are simply using the "opt out" requests as a way to validate the data, but it's just as likely that the tool works with the brokers to confirm information instead of actually removing it.