> HN is low on ad hominem attacks, excessive straw man arguments, there is a good amount of polite disagreement, and people are often amenable to being wrong.

That's is due to active moderation, but it's orthogonal to being in a bubble. There are also some very similarly moderated, polite communities on other platforms, even Facebook, but they're still bubbles. People on HN are already self-selecting to an extent, and if you stray to far from the core audience, you'll be downvoted to dead.

That's how the forum is designed to work, but it is definitionally a bubble.

> If this seems no different from the big commercial platforms to you, I frankly don’t know what to say, to me the difference is plain to see.

It is no different to the other well-moderated communities on the other commercial platforms. The only difference is that you like this bubble more than the others.

> That's is due to active moderation,

Just, FTR, there's always been the problem of how much moderation is required to keep the discourse (in a group) flowing without being so restrictive as to only be about the moderators.

See IRC, which (IMO) can be over-moderated, channel ops used to be very much about themselves, vs Usenet, which had no moderation at all (and was "destroyed" by google groups making access trivial for troublemakers), through to current things like Reddit which have some moderators.

It's (IMO) exactly like governance IRL - some countries overdo it, and some underdo it.

Please describe what it would be like if it were not a bubble. If everything is a bubble, the concept is worthless.