I think I can answer that! :)

UA metric, which gives the ranking, applies to every account on Steem.

UA-based curation from @steem-ua is what is performed for the accounts of delegators (who don't refuse the reward).

Yes, it would be an idea to add the possibility to check the UA ranking of any account, and I think that's what @scipio has in mind when he made that remark about @steemchiller's SteemWorld.