I know it feels good knowing someone's read your post and bothered to comment too.

Too often lately I notice many posts with heaps of votes, but only a few views. (At time of written this comment I see this article has 77votes and only 39 views... maybe some of those upvotes will come back later to read it, but I doubt it).

But if you're upvoting comments means people will come back next time, the go for it! It's a reciprocal relationship, like you said, and everyone benefits.