Different people pay attention to different aspects, so the flexibility to vote on multiple aspects at once or differently from overall vote is unnecessary.
There’s a limited sense in which this is true—the adjective voting on Slashdot wouldn’t benefit from allowing people to pick multiple adjectives, for example. But being able to express a mismatch between overall upvote/downvote and true/false or agree/disagree may be important; part of the goal is to nudge people’s votes away from being based on agreement, and towards being based on argument quality.
There’s a limited sense in which this is true—the adjective voting on Slashdot wouldn’t benefit from allowing people to pick multiple adjectives, for example. But being able to express a mismatch between overall upvote/downvote and true/false or agree/disagree may be important; part of the goal is to nudge people’s votes away from being based on agreement, and towards being based on argument quality.