That's the same as having them within the same LAN. That makes https unnecessary, but you'd still have to remember ip+port combos without a domain. The domain doesn't need to be publicly registered unless you want services to be accessible externally without a VPN connection.
I only allow a couple of my services to be accessed directly via public domain, mostly for sharing with friends. The rest you've gotta be within the LAN either by wifi/ethernet or a VPN that I host.
I have not said the data is incorrect, I have said it is only representative of one type of piracy, exactly as the authors of the linked article as well as the original source of the data have.
I've simply made a point of highlighting this fact as the tiles don't make it very obvious.
Once again: