I look at comment upvotes as two-fold. 1) it lets people know I've seen their comment. I guess this is more important if I don't reply, but it still serves the same purpose. I do the same on FB (on the rare occasions I'm there) and other social media. 2) Yeah, as you say, it's kind of a thank you. Unfortunately this is less a reason because any upvote less than 3 cents will go to dust. So.... well, we're back to the first reason 😃 I do hope to grow my account enough that my 3-5% upvote on comments is above that 3 cent limit. I'd love to give like dime upvotes on comments at least eventually.