[bowlich]

Just because there's no public facing service sitting on a domain doesn't mean that domain isn't in use.

I have a domain whose only public facing service is just some picture I took. Am I using that domain? Yes, sure. It hosts all kinds of intranet services -- a few are whitelisted to other external IPs. Could I set up my own DNS on my network for those services and not own a public domain for them? Sure. But then I need to make sure anyone joining the network is first configured to use that DNS, instead of just joining the VPN and now the services all publicly available to you.

As far as Joe-public is concerned, I'm just squatting on that domain and not using it.