There are some online communities in which that kind of thing is ok. HN is not one of those.
The word 'scabrous' means "dealing with salacious or indecent material". Feel free to inspect the image, I guarantee it's safe for work.
The first meaning of "scabrous" in my dictionary is "having a rough surface", and that's how I meant it. There's a long tradition of using that word to describe rough-and-tumble discourse, and it seemed fitting. You didn't just smack another user, you smacked them with a pointy implement (a link to an insulting image). That's not ok on HN. Neither is smacking people without a pointy implement. And telling another user "You're a liar and a coward, and you know it" is right out—a bannable offense, although we didn't ban you for it.
I'm insisting on this more than usual, because we don't want the pugilistic approach that is popular in some related (by subject matter, at least) online communities to take root here. When commenting on HN, please eliminate incivility from what you post.
Your position about the place we want HN to be is clear, but I still believe the image is not insulting or offending anybody in any way. Those who flagged it, could they have misinterpreted it as an insult to the developers? An insult to the users? An inappropriate "scabrous" picture based on the URL? Or just as an attack to a program that needs our praise?
I realize now that I was being too cute pulling out the old "scabrous" to make what is really an obvious and mundane point, and ended up confusing things. Sorry. I get bored sometimes and throw in variations which HN moderation comments are obviously not the place for. Let me try to be clearer.
There's nothing at all wrong with that image per se. It's great. I've made more than my share of Rube Goldberg analogies and know exactly where you're coming from. Had you linked to the same image in a thoughtful comment about overcomplicated systems, with no trace of incivility, of course it would be fine. It was only a problem in this context, i.e. a drive-by potshot in an inflamed discussion on a polarized topic.