IIRC from the original report, the claim here is that even "gaming" these metrics leads to the desired result, as you can't game these metrics without actually improving your processes. I tend to agree.
Too bad they became a giant ad machine. Ads on top of the page, ads on the sides, popup ads, endless "articles" which are just Amazon affiliate links... No, I'm not salty, why do you ask? :/
Each remote instance stores the posts from every other instance's communities, from the point at which the first person viewed (...or subscribed to...?) that community on the remote instance. That way the instances are less dependent on each other's uptime and can optimize their queries, giving a better user experience.
Btw. this also means that there will always be some delay before posts/comments from one instance show up on another.
Why would you use blockchain to track shipments when you can easily do the same with a standard database? What would be the gain?