I share your thoughts about those who comment and do not vote.
When I read a post I like I always vote and if I have time I leave a comment and never the other way around.
When I get a comment I always vote on the comment as you do because the person who reads and comments on a post of mine has taken time out of their time and I think it is fair to vote on that comment.
I have never paid attention and never checked if there is someone who comments on my posts but does not vote for them and I will pay attention from now on.
In all likelihood those who comment and don't vote are often also those those who self-vote, want to receive and don't want to give.... !LOL
I don't know if adding this check (self vote) to your script is difficult to do but it would be a nice addition that would detect a bad hiver!
When I read posts like yours with Phyton codes I feel like taking up programming again but it's been a long time since I studied programming in college and today I have very little time for the activities I would like to do.
I must try to follow the instructions you gave in the comment to revisesociology