> Maybe predictable conversations, and a bit of a echo chamber, is more appripro? [...] It seems like we have hashed out the important scientific stuff, and most issues computer related.

I think you're totally right with the first sentence I've quoted. The second has some truth to it, but I think it's a more personal effect than you seem to be acknowledging.

The most common complaint of long-time forum members is that the signal-to-noise ratio has gone down. In reality, the signal-to-noise ratio could stay the same, but for any individual community member, we will personally find less signal in the noise. The discussions will inevitably become predictable to us.

When we first join a forum with a particular focus, we likely have an incredibly incomplete view of the topics being discussed, or at least that community's interpretations of those topics (some of which might change our mind). We'll have lots of epiphanies. We'll connect a lot of dots that we hadn't connected before. We'll have real world experiences that we can anchor to discussions in the forum, allowing us to bring our life context into the forum and the forum context into our lives.

Over time, though, we'll be learning less and less from the forums. The forum discourse can initially advance somewhat as we come to useful consensus on some topics, and as the earlier members have more life experiences. For any forum that allows new members, the discourse is bound to hit a steady state of much more slowly evolving discourse. In the long run, forums likely evolve at roughly the same rate as society as whole.

The forum still fills a very useful function for those new starry-eyed members who have a lot to learn and much room to grow. For them, the adventure and discourse and overall experience is nearly as good as it was for the early forum members.

Meanwhile, those early members continue to grow at human rates, not society rates. We outgrow the forums. We start to see similar points over and over again, ones we've already argued to death and assessed for ourselves. We've personally experienced supporting and contradictory anecdotal evidence for many of the forum's consensus viewpoints. The "signal" at this point mostly comes from discussing entirely new events in the forum's focus area. The sorts of things where you might say, "I wonder what HN thinks about this?"

Therein lies the rub. As we personally have discussed to death the technical topics that drew us to HN, we almost wish to give "the HN treatment" to broader areas, especially philosophy, politics, and other current events. But we are not experts in these areas. It might feel exciting to us to discuss these things with our peers, but to anyone looking in from the outside, we're a bunch of bumbling idiots who think we know it all. If these topics start to dominate the conversation, the forum is no longer interesting to newcomers. Foremost experts in these areas have little reason to visit the forum, so any advancing discourse is much slower than it was for the original forum topic.

Sorry, I'm kind of thinking out loud in this comment. I guess my conclusion is that it's probably best to strive to keep the forum on topic, even if it gets boring for the oldtimers. I think it's totally fine for members to realize they've outgrown the forum and move onto other ways of spending their remaining time on this planet. We can take some satisfaction in the role that we played in the forum's early growth, and we can be grateful for the role that it played in our growth. And we can let the next generation muddle on in our stead, experiencing their own adventures while moving the center in their own direction.