To explain, I think upvoting comments is extremely important, because that´s encouraging engagement and interactivity (a key feature on this social platform compared to others), I do upvote ALL meaningful comments on my posts to at least above the dust treshhold.
But comments are very different in nature and not all warrant an upvote. A comment trail is fine, but only if those are manually selected. The header was about auto-voting comments which is a completely different story.