Currently it looks like this, yes. But this will change. I believe that UA will get adopted by many steem services, and the code is planned to go open source soon as well, so that black box will get "removed" soon as well.
I do think that UA will be implemented in many more places. I'm just mentioning a trending feed based on a post's UA, and not it's payout value! This would possibly be something everyone could benefit from. But because UA is still very new, there aren't many use cases out yet. Stay tuned for the new ones!

PS: I rather see @steem-ua as some kind of Proof of Concept for that new reputation metric