I agree with feeling uncomfortable making jokes at others' expense here, and I definitely agree with @elixiadragmire that laughing at people for misstepping isn't as harmless as it might've been intended.
But at the same time, I feel like this general sentiment of "hey, people who want their comics to sustain them have to promote" is well-meaning but perhaps misplaced? Knowing how to promote EFFECTIVELY is what gets you more readers and more people who are invested enough in you to support your work.
If a creator has been thinking that trying to link to their comic in every single reply is necessary to promote their comic, because they need it to do well, then learning that this can turn people off from their work should be something they eagerly jot down in their notes! I don't wanna make fun of someone who's contriving a link to their comic into every single post, but I also don't wanna be like "nah, keep doing that!" when it really is a thing that I believe can hurt you in the long run.
This isn't about promotion in general, or linking to your work as often as possible (those things are good!!), it's about unnaturally cramming a promotion into a conversation where it feels off-topic. That can hurt your ability to promote your work -- if you come across as rude and self-serving, people are less likely to want to check out your comic!
Fair point! though I think there's still a time and place. One off-putting example I saw a while ago was a thread asking "does anyone else feel discouraged about their art sometimes" and kind of explaining their personal struggle and looking for advice and sympathy, and one response was essentially "nope I never get discouraged about [LINK: MY COMIC]!"
Like, yeah, you can do that..... but you're not really doing your comic any favours if you do.