> It sounds to me like you only have experience with some of the larger subreddits like r/pics.
As I said in my post, I frequent podcast subs, which are usually on the smaller side to things. Sure, you can pin posts, but only two at a time, which means they often get dropped and switched. And unless they're extremely recent (so you're pinning posts all the time), as soon as they get dropped, they disappear. Spent 30 minutes writing a post to a pin discussion that you posted minutes before moderators switched the pinned post to something else? Chances are, no one's ever going to see it.
But a bigger problem is how nothing gets bumped to the top in those places. If I randomly stumble across a 5 year old discussion on IMDB and post a comment, it's going to be bumped to the top of the post list, and plenty of people will see it. If followed a link from something pinned to the top of a Reddit sub to a 10 day old discussion and make a comment, it's likely no one will see it. The only way people would even know there was a new comment is if they kept checking all of the dead conversations that have already fallen off the front page.
And the upvoting/downvoting exacerbates this further. It's not just that you're limited to the most recent posts if you want someone to see what you've said, but you're often stuck replying to the most upvoted comments to that post.
I'm surprised if I get a comment or upvotes on site like Reddit or Hacker News after a couple of days. On the webforums I frequent, I often get them after _years_. If this were a forum, I'd probably be making this post later tonight or later in the week. But on Hacker News, if I don't make it in the next couple hours it's likely no one would ever see my response.