You're exactly right!

Where I go to look and see if the commenter has replied AND upvoted, I noticed something...

michelle.gent curation reward: 0.025 SP for @sequeira/re-michellegent

I got a reward for upvoting your comment. It was a small reward, but a reward, nonetheless.

This is what people don't seem to realise.

You give and you receive.

It really is that simple.