Downvoting for disagreement is encouraged? That's news to me! Not welcome news either, because I like the idea that the "quality" of the comment matters more.
Personally, while I don't downvote for disagreement, I definitely will downvote (what I perceive as) disingenuous questions — There's more productive ways to express an opinion.
pg (the site's creator) once wrote that it's ok[1], and the current mods have cited that post recently[2], indicating it's still the policy.