I could add quite a few more generalisations myself while I'm at it, HN isn't solely populated by hyper intelligent, well reasoned, logical doctors, who form their ideas completely independently of everyone else. There's going to be group think, there's going to be like minded individuals attracted to one another, that's human nature, deal with it.
I don't even think it's an ad-hominem. HNers are generally argumentative gits (generalisation), who like finding an exception/hack/new way of looking at something (generalisation). I have no problem with some of those schemes being described as 'hairbrained' (sic although actually... ), but that's why I come here, because if people didn't think that way they wouldn't be Hackers.
Not sure if that was for comedic effect but I laughed out loud! A brilliant demonstration of the behaviour you describe.