Hi Daniel,
Good point! We were thinking about this, too. But then decided against it, at least for now, for the very reasons Tim and Howard mentioned.
In popular threads with many replies discussions sometimes diverge quite a lot from the subject of the original post. And while we could pin the original posts to the top, a new person would still need to go all the way back to get to the more relevant replies to that first post.
We’ve instead implemented some tools that should make it easier for you to find your latest posts and replies and skip everything you have read already, and very soon we will have even more features in place for you to do that.
I hope this helps.