You know I upvote comments. I do think that it encourages engagement, but you have to watch out for people who are just fishing for votes. Some of them show little sign of having read the post and you can see they comment more than most so they can't have time to read much.
I do not check if these people upvoted my post. In many cases they could not have much effect anyway. Their comments just need to have value.
We need to spread the Hive rewards to more people to keep them coming back and build more activity.