Archiving helps me know more about myself. Primarily, I use forums as a way to archive my viewpoints and how I have reasoned them. It's spectacularly rewarding when discussions devolve into an argument and I know specifically how and why I came to a certain conclusion, because I can reference thoughts that I reasoned before. Rarely, I find my views challenged in a constructive way that informs and changes the mind of one party or the other...if only on tangential topics. That's always nice.
It's also handy to listen to the echo chamber to get ahold of the zeitgeist of that particular group, which is useful when interacting with other people in real life that espouse particular aligned views. Now you can have an interesting conversation, you might not have had otherwise, which is a practical sociological benefit.
Arguably, Hacker News is a lot of an echo chamber too.
What’s the point to get your “2c” heard on Hacker News? Hacker News users are even more of a minority than Redditors.