Thanks for the correction, I read the wrong number! I’ve edited accordingly.

Indeed. Activity pub includes favourites and boosts.
Lemmy uses favourites as an upvote. Kbin does too, but kbin also allows boots and it considers that a boost (which is like a retweet) is a more significant endorsement so sorting and reputation is based more on boosts than on upvotes.

Circa 60,000 active users, but whatever…

You are rather missing my point. Because it sorts on boosts rather than upvotes it surfaces different things in the federated ‘all’ feed.

Edit: As corrected below it’s about 10k monthly active users, but that’s still circa 10% of the whole threadiverse (kbin + Lemmy) and only Lemmy.world is larger than kbin.social

Have you tried kbin? Same content in that it’s Lemmy compatible, but slightly different sorting algorithm which (in my view) seems to result in a more rounded/balanced set of posts being promoted.
Yes there a different set of issues - it’s earlier in it’s development phase, but developing fast (collapsibling comments is being worked on, API (and therefore 3rd party apps) is imminent, many other improvements are developed and expecting to go live this month…