Wouldn't it be interesting, then, if instead of editing a metadatum, clicking the arrow made a duplicate of the post (or, rather, a Post object with the votee as its prototype), which then stacked under the original...
"'A stacked comment' posted by bob, joe, fred"
Should I upvote every other article to express my opinion? :)
People who agree with an article/think it's important/useful have an immediate way to express that in a useful way - an upvote.
You don't have the same capability if you strongly disagree with an article, see it as unimportant, not relevant, or off-topic. I still think that's a shame.