That may be true for something like a HUD or where we're really overwhelmed with info that is fast and reaction time is paramount.
But you can read a hackernews thread one line at a line and never get overwhelmed, right? I literally have never felt overwhelmed looking at the threads (which are also organized into local groups already etc).
I read it for pleasure and engagement, it's not something I want AI to automate away.
And when you say "continue the conversation there", do you mean use AI to write comments? If so, then this is the opposite of what makes HN HN.