[pythonaut_16]

I think the term echo chamber specifically denotes something bad.

An echo chamber happens specifically when a group's internal belief's enter a positive feedback loop and become insulated from any external (and often internal) dissent.

What you've described sounds more like a group with common belief's that has not devolved into an echo chamber. And that is what we should all strive for.

[clairity]

yes, this correlating effect is specifically argued against in the book 'wisdom of crowds', which discusses the conditions under which group decisions are better than individual ones. echo chambers are defined by their strong correlative impulse, which means they're statistically much more likely to significantly deviate from objectivity.

another relevant phenomenon derived therein is that a range of opinions, most of which are wrong, is completely normal and acceptable, as far as reasonable group decision-making goes.

but correlation of opinion is the core issue here, and human social dynamics constantly corral us into such correlations. only folks sufficiently and intrinsically principled have a strong enough will to incur the social costs of having truly independently-derived opinions from the herd (which doesn't guarantee objectively better perspectives either, but does help the herd hedge against catastrophic over-correlation).