If you have one of those cars that can be used as a boat. And you only ever use it in water and never on land, it doesn't really make sense to me to exclusively call it a car. Even though it factually is one, it acts as a boat. At least call it carboat.
If I have a VPN, but it's sole purpose is to take all the traffic that knocks on it's network-adapter and shove it down a dev/tun and vice verca, why can we not say (with the goal of clear communication and precise descriptions) that it effectively acts as a proxy ?