Reddit is a huge danger to society. There's no doubt that subs about specific non political (and non popular) topics are hugely beneficial, the overall damage the echo chambers do still outweigh these benefits.
Suppressed debate is almost universally due to biased/captured moderation teams aggressively using bans.
People shouldn't be blocked from commenting because their karma goes negative. Spamming, hateful talk, etc should be a completely different system. Just because what you say is unpopular (in one place mind you) doesn't mean your words should be hidden.