Yeah, if there are signatures then it doesn't matter. But often both are a miss.

Eg the key from https://docs.docker.com/install/linux/docker-ce/ubuntu/#set-... doesn't have signatures, and isn't on the keyservers.

Of course an unsigned key missing from the keyservers still has the advantage that on subsequent installs/updates, the previously downloaded key persists. And you can keep the initially downloaded key in your CI configs.