Ok, one more upvote before my break. I noticed @pressfortruth doing this as well. I added some information to bring something to his attention, and nothing.
If I comment once, and there is no response, I usually just give them the benefit of the doubt, because I understand that sometimes it's hard to respond to each one, or life got busy, or whatever. If it happens a more than that, I'm insulted, and am much less likely to support their post in the future, even if I like it.
Engagement is integral to the health and identity of Steemit. Some people are better at it than others, but either way it shows the author that you valued their post and that you respect them enough to engage them. Accounts that post and don't engage the people who support them come off as ungrateful to me.
Yes, one time, or a few times, ok, but if it's every time... psshh. It's a lack of courtesy to someone who took that time to give you their attention and talk to you... to just ignore them each time...