I usually don't comment because there is no reason.
Usually my comments are like a reply to the authors description, so if there's nothing to reply I often don't comment, cause it feels like i'm just reading instead of interacting with someone, also If the story isn't catching my attention or got me lost I won't comment, maybe just something like; "god i'm lost, gotta re-read the whole thing" So basically if there isn't any specially interesting in the page I won't comment, I need to see a cameo, there should be a plot twist, an improvment or an interesting composition overall, I need to note something in page to comment, otherwise it's just meh, and actually over the time I'll stop following the comic.
It indeeed bothers if the author does not reply (in the case of comics with little fan base) but for me isn't kind of a big deal, it bothers but i can rol with that, An example of a great author that is commited to feedback is Harkill, in his comic HeLL(P) he often replies to coments, his description seems also like a coment or a gag about the comic itself, and there's always an easster egg on every page, everything going by the hand with stonnishing and marvelous visuals, it just clicks