Its called cognitive dissonance. People spend a lot of time and money trying to make themselves harder than the nasty big boys who beat them up at school by spending years learning a martial art, and when someone suggests that maybe it isn't as effective as they had prayed every night, they start getting irrationally angry at the thought of all that wasted time and money and go into denial. As a result, they just can't stop themselves flaming the thread in a fit of fury and indignation.