There's always a healthy middle ground: form a community with healthy cultural norms in matters of politeness, courtesy, intellectual rigor - all elements of fo

There's always a healthy middle ground: form a community with healthy cultural norms in matters of politeness, courtesy, intellectual rigor - all elements of form - while encouraging the greatest possible diversity of substance. Make it clear to people that be adhering to the norms of form, they'll be a welcomed member of the community, without being censured for the actual substance of their arguments, but merely argued against politely by those who disagree. (Sure, there are people who take any counter-argument as a personal insult, but that's just one of the things we need strong cultural norms against.) I suppose it's a challenge to maintain this sort of pattern as a community scales, which is why sites like HN, Reddit, StackExchange, etc. all try to incorporate incentives and constraints into the mechanics of discussion to attempt to reinforce certain styles of participation, with varying success. In this situation, a simple mechanic to prevent people from doing what OP is complaining about would be to prevent comments from being deleted once they've been replied to. It bugs me when I see long streams of deleted comments on Reddit, too - it'd be an interesting experiment to treat posts and comments in a discussion forum like wiki pages - freely editable at any time by the poster, but with the full edit history always available to see.