Well said!
To share with you my take on the same topic: indeed @steem-ua is one use case / application (out of many!) of using UA data, and indeed the objectives of @steem-ua are "getting in & keeping in" users on the entire Steem Blockchain. To create a certain mechanism that incentivizes and rewards "good behavior" from a community perspective. If you shitpost, the value of that shitpost is still "something" but not as much as it could have been if you really gave it your best shot to produce top quality content. The algo identifies - pretty accurately as well - how others interacting with the post value that post.

For example, somebody in this comment thread wrote he/she is of the opinion that @berniesanders has a too high UA rank. I don't agree to that, because the entire Steem network is taken into account for him to have that UA score / rank. Does @berniesanders deserve an upvote, being a @steem-ua delegator, when "shitposting" (as he calls it himself) a picture of a toothbrush and a lamp, and/or create a contest / challenge for others to publish similar pictures?I'm of the opinion he does deserve our upvote indeed. You can agree or disagree or think whatever you like about his actions, but it is a fact he is influential on Steem, and that is what UA measures! Yes he is influential, and therefore yes he deserves a high UA_Account score.

Now, the interesting thing - as far as I'm concerned - is this: if @berniesanders decides to publish a masterpiece of content and spend a ton of time on writing it, then I am quite sure our algo is able to identify that that post of his deserves a higher upvote than his other posts. Intuitively, that justifies the algo functions as intended.

Also, suppose some random, unknown, rather new, not influential account delegating to @steem-ua would publish a similar example post with a challenge to post a picture of a toothbrush and a lamp: would that similar post deserve the same upvote? No! Because close to zero people know about that account, their post will not receive much attention.

And this brings me to an important distinction to make: @steem-ua is indeed an experiment to value "content quality", about any topic in any language, but not by the content alone, but also - or even mostly - by who (based on each post's author, voters and commenters) publishes and interacts with it (!!!).

A one photo post with (close to) zero additional textual content can have value, but who's to decide, and by which objective criteria, if that piece of content is "quality" content, and/or has "more or less quality" than a 500 word article? @steem-ua lets the giant network of follower relationships and the witness stake and their followings decide.

Is that perfect? No. Can we distinguish top quality content, always, 100% of the time? No. But it does work reasonably well.