Lots of people comment without upvoting, some saying they upvoted without doing it (don't know where they have their heads though as it's right there for everyone to see).

I think for the majority, the upvote left undone is partly due to previous experience where the only real way to support was by commenting (even though you could give likes). Still though, I'm not sure: it's something I've been mulling over. Seems to me that people are still not that aware of just how important upvoting is as a support mechanism on Steemit. I've begun to subtly educate on the subject asking everyone to support by upvoting.

But when someone is gaming the system, that's another issue entirely.

Good post, and thanks for your efforts.