It's what "flag" is for:
> Please don't complain that a submission is inappropriate. If a story is spam or off-topic, flag it. Don't feed egregious comments by replying; flag them instead. If you flag, please don't also comment that you did.
No it's not.
There are a lot of stories that aren't worthy of flagging, but they're just low-quality.
And I've seen people abuse flagging because they treat it like downvoting. Flagging removes a story from the front page entirely, whereas ideally downvoting would simply deprioritize it, i.e. a bunch of downvotes would move it from #5 rank to #60 or something, not get rid of it entirely.
I've definitely had to e-mail the mods a number of times to restore a flagged story that was entirely appropriate, but which a few users simply didn't like. It would be much better to have a downvote button, and reserve flagging for actual spam and inappropriate content.
This article is neither spam nor off topic.