Content doesn't need to be managed in this way because worthwhile stories are upvoted accordingly regardless of the topic; stories that are not worthwhile/relevant are not upvoted and vanish on their own lack of merit.
Flagging is used by people to silence important discussion more than anything else now.
The truth is twice as hard to move as a lie and flagging is another tool used by those that want to subvert the meaning of facts, and undermine democracy/freedom at a core level.
HN mods should have the ability to flag still but I woudl argue it should rarely be used.
Case in point: this post will likely be flagged by those that want to continue abusing the flag capability of HN and silence this discussion.
Where's the evidence of this?