[acdha]

It’s also dangerous if those ideas are widely circulated to people who wouldn’t otherwise have had them reinforced.

What this comes down to is the level of good faith at play: hearing dissenting ideas is good if you’re in a place to take them seriously and the dissenter is being genuine and willing to discuss them in good faith. If those aren’t true, it’s not a win: nobody benefits from giving a liar or propagandist a podium and someone who can’t agree on some kind of objective baseline won’t be able or willing to adjust their beliefs.

[deadpannini]

> people who wouldn’t otherwise have had them reinforced.

You mean people without access to niche communities / echo chambers?

I grant there are people ready to embrace destructive ideas, but the fraction of them that don't already have access to those ideas is small enough to be irrelevant, especially in the age of the internet.

Better to have them out in the open, for the reasons I mentioned, and moreover, because it's better to have an accurate view of what they think.

[acdha]

It’s more the people who might get pushed to the next level as they get positive reinforcement and, especially, as more moderate people leave because they’re tired of dealing with the zealots.

Extremists don’t care about disagreement – they’re there to talk, not listen – and if they see a few fellow travelers they’ll start to tell themselves their position is mainstream.