This seems like a rarity. The vast majority of HN discussions don't have this situation, and it seems odd if the only purpose of HN voting is to upvote "celebrity" comments. There are much better places to follow the comments of celebrities than on HN.
> the alternative of randomly selecting people to govern also has its problems.
I strongly believe this is actually the least bad form of government, and vastly superior to elections, which are glorified high school prom royalty pageants.
> Do you know any platforms which have successfully done the randomisation thing?
No, though I have no idea what "algorithm" Twitter uses to determine the order of replies in a thread. (Probably not totally random.)