But what requests would it even make? If you opt out you're effectively telling it to _not_ make any requests.
Unlike GDPR, which uses a website as the gate for all cookies, the ad industry also has self-regulatory programs. Participation in these programs require that a website allow a user to opt out of all ad networks present on their site. TrustArc built a module to do that: https://preferences-mgr.truste.com/.
If you run the tool there, it will make a call to the ad networks listed. Of course if you're running an ad blocker, the call will get blocked and it will look like the tool doesn't do anything.