Vlad I made this thread instead of contributing because the stats page is not open source as far as I know. It's not a big deal, but private / closed beta and public / open beta mean specific things, and the Assistant falls squarely under the latter.
https://en.wikipedia.org/wiki/Software_release_life_cycle#Open_and_closed_beta
The difference is that if it were a closed beta, only people that you actually invite could use it. Since anyone can join without being invited, it is an open beta. This confusion might lead fewer people to try out Ultimate for access to the features. I know I was hesitant, because I wasn't sure if I would be invited.
I'll open up an MR for the documentation though.