Is that just because people end up upvoting comments that say things like "yeah", "yep", "great post", "thank you" , etc?

I feel as though a single vote on the post, without a comment, should also be noticed by an author as opposed to the whole chain of

"Wonderful post"
Vote
"Thank you"
Vote
"You're welcome"
Vote
"Anytime"
Vote
"Uselss bot call"

Vote

... Maybe if i want to get more sophisticated with my analytics, I can look at a combination of the users with the longest reply depth on comments, the average word count, and if its lower than say... 5 words, then I'll put them on some sort of naughty list of not being able to communicate their thoughts in any meaningful way.

You're definitely not on that list, as far as I know :P