The Nameless Wiki federation chooses not to rely on DNS but is hardly a secret who is who.
ICANN requires that domain names be registered under a person's name. But this can be a representative who chooses to keep the real owner secret.
IP addresses are allocated by internet providers. They keep track of who has them. They probably just know an email address and a credit card.
I choose to be Ward Cunningham in nameless. That is also my professional identity. But my government insists that I drive and fly by another name.
When I claim Node sites it exposes my email name, ward. I'm firstname.lastname@example.org and have been for decades.