Russell is discussing the purpose of Planets, the feed aggregators many of us enjoy. I don't think it's ever really been enumerated, and it probably should. But I bet it's different things to different people.
I enjoy the Planets for the rich and varied insights you get into peoples' lives. We're not all one-dimensional geeks, though I imagine those reading Planet Linux Australia might not have worked that out since I've been censored there.
Russell discusses etiquette for the planet operators. I strongly agree. I've found myself added, then censored from some Planets without any interaction from me -- yes Planet Linux Australia's operating cabal, I'm talking to you. Without some sort of policy, it seems these sites are just run at the whim of the person with the password.
The idea of separate Planet installs, one that's filtered to be solely on-topic and one that shows everything, is a good idea. I think that would resolve many of the complaints about off-topic posts for those who aren't interested in everything. Another thing I'd like to see is the banning of Twitter. The inane wibblings of people who are clearly deranged isn't something of any interest. And there's certainly nothing on-topic in there. Less coherence and thought than goes into a text message seems to be applied to average Twitter post. Enough already!
One thing I would recommend is to not run the official Planet software. It's breaks badly on perfectly-valid feeds, and seems to be abandomware. Try Venus instead, which has refactored much of the code.