This is not to say that all sides must be held to have equal weight. Flat earthers should only get a passing mention on the article about the curvature of the earth, though they should be mentioned. Breathinarianism should be barely mentioned in an article on human health.
I've found, when I was working on contentious articles on Wikipedia (all those many years ago now!), that neutrality always highlighted extreme views and held them to the light of day - they seemed, if anything, more bizarre and absurd when presented in a neutral manner. That's really why Scientologists hate Wikipedia, IMO.