https://gwern.net/doc/technology/2005-shirky-agroupisitsownw...
I wonder what the cut-offs are for "group is too small" and "group is too large", but that certainly depends on the subject the group is about. A philosophy book reading group probably doesn't work well with the bestselling crime novel audience.
Of course, all of this is quickly-written thoughts for a HN post. Maybe at some point I'll edit them down and post them properly, but I need to discuss it with more people so I'm sure my thoughts actually strike reality.
Thinking more about it, you see this both in forums and IRL: https://meaningness.com/geeks-mops-sociopaths (Minus the trolling aspect as in groups there is no anonymity as in a forum.)
Often rich people associate only with people of equal wealth in cigar lounges or country and golf clubs. It's to be expected many hidden filters apply to online and messaging culture as well. Your C.S. Lewis quote and idea of how this applies even to HN is very positive. Indeed I only could reply because I saw your article at the right time in my feed and happened to be online and browsing entries.
In the past I liked to read a lot of Scott Alexander Siskind, SSC/ACX and LessWrong, even if often disagreeing with some points. Don't be afraid to be wrong when blogging. It is an iterative process and to be honest, I would like a blogger who does a review of his old posts after a year and write where their opinions changed. Not in full, but selecting a few opinions that got refined over time. And don't fear your audience being small. Often I vote up content because it is different or prompted me to self-reflect.