It would nice if there were a way to downvote submissions to indicate they're of low quality that's separate from flagging. Flagging is rather heavy handed in that it can cause a submission to become [dead] since it seems to be mostly intended for marking submissions that break the guidelines.
I think after nearly 19 years it’s pretty well settled that downvoting of stories won’t be happening :)
The principle is that we don’t want a battle between upvotes and downvotes to determine rank, because that would set the wrong incentives (e.g coordinated downvoting of stories to help a particular story move up the rankings).
The guidelines include what is on-topic/off-topic, and the most significant criterion is whether a story gratifies intellectual curiosity.
If you earnestly feel that it doesn’t, then it’s fine to flag it as being off-topic. Otherwise it’s just not to your taste, in which case hit “hide” and upvote stories you do like.
See also: https://news.ycombinator.com/item?id=373801