Moderator’s note: @doubtingthomas Please don’t post offensive stuff (e.g. about incest) as a throwaway example. It’s problematic plus unnecessary.
If you actually want to talk about a taboo/problematic/99%-of-people-disagree/etc. type topic, on purpose, because you have something important and productive to say, that’s one thing. You can do that (at least in Unbounded – I don’t think the really offensive ones should be brought up in Friendly at all). But then you should pay attention to what you’re doing, introduce it in a reasonable way, say why you’re bringing it up, acknowledge the downsides or problems, etc. Put some effort into it. But don’t bring them up offhand when you aren’t focusing on them.
An example that isn’t very offensive would have worked just as well here. There’s no benefit to shocking or offending people by bringing up incest. It distracts from your point and alienates readers. And it makes it hard for anyone to disagree with you or debate you, because then they have to talk about a subject they’d probably rather not, and risk you arguing back and then they’re spending ongoing attention on an uncomfortable subject for no good reason, while trying to talk about something else, and risking you saying even more outlandish stuff that they don’t want to deal with.