I'm not at all sure that there is any advantage to spelling out when people who have downvoting privileges should exercise that right, since such advice is ultimately strictly precatory anyway.
As sumelic says in a comment above, the advice to "Use your downvotes whenever you encounter an egregiously sloppy, no-effort-expended post, or an answer that is clearly and perhaps dangerously incorrect" doesn't say "Only use your downvotes..." Indeed, it doesn't put any practical limits on when to use downvotes at all. But it does suggest that downvotes are most appropriate in what I think it is fair to describe as instances involving exceptionally poor submissions.
It seems to me that this language can easily lead to hard feelings when posters concludes that downvoters must have judged their submission to be egregiously sloppy, effortless (in a bad way), and/or clearly and perhaps dangerously incorrect. Maybe the site's policy would be clearer and less susceptible to misunderstanding if the Help section said something like this, instead:
Casting downvotes is, in general, an unregulated privilege. Downvoters are under no obligation to explain their downvotes or to identify themselves as having downvoted a particular post. Some downvoters limit their downvoting to questions and answers that they deem egregiously sloppy, lacking in effort, or factually incorrect. Others downvote questions and answers that they consider excessively simple, lacking in evidentiary support, or unduly opinion based. Still others downvote questions and answers that they find uninteresting, unhelpful, or (in some other respect) unsuitable for this site. It is even possible that some people downvote questions and answers that, although acceptable in point of research and presentation, reach conclusions or make points that the downvoters disagree with.
Here are five important things to understand about downvoting:
Downvoting is a privilege that users earn by acquiring enough points on this site to establish themselves as being presumptively responsible users.
Downvoting (like upvoting) is part of an assessment system that is designed to be anonymous and that therefore requires no explanation or justification for particular votes.
Cumulatively, downvoting (together with upvoting) tends to promote better questions and answers, and restrain worse ones, by helping the one to rise and the other to sink.
Downvoting can help a poster recognize that a submission may have weaknesses that the poster was not previously aware of, and thus encourage the poster to improve it.
Everyone gets downvoted occasionally, whether the downvoted post deserves it or not. If you recheck a downvoted submission—particularly if it has attracted only one or two downvotes—and it still seems sound, consider the possibility that the downvote is not a profound and authoritative judgment on the quality and usefulness of your answer, but rather one person's opinion, expressed at the click of a button, after an unknown amount of deliberation, for an unknowable reason. Then let it go, and move on.