I'm not sure a ban on irrationality is exactly what you want. Even psychosis can be a very creative and valuable moment of insight or growth, and people inclined to (admittedly unreliable) irrational thought need to be supported by others rather than shunned. See also this recent article: http://arstechnica.co.uk/science/2016/11/election-ourage-mor...

Also, HN in particular can have a kneejerk objectivist flavour that discourages intuitive, unconventional discussion. Dismissing people who seem irrational is not a good way to encourage healthy cognitive diversity, and we could do with less of it.