@kevinmarks well again, that's dealing purely within the realm of mastodon, which i think we can agree does not strictly *need* webfinger, but i still think it is useful for interop
note that the mastodon web domain and webfinger domain do not have to be the same, either -- i could host mastodon.trwnh.com and have a profile at mastodon.trwnh.com/@a, but still use the webfinger address a@trwnh.com for consistency with my email and xmpp (although with that said, i do not wish to run mastodon....)