Unfortunately it's not that simple. The flagging system works well, arguably better than the upvoting system does, but you can't just rely on these systems in an unsupervised way—it leads to suboptimal outcomes. Another way of putting this is that moderation is necessary to jig the software+community systems out of their failure modes.

You can of course argue that I've made a wrong call in this case, but the point I'm making here is different: you need moderators who make judgment calls, including to override flags sometimes. And of course no one is ever going to get the calls 100% right; we have failure modes too.