I think its more likely that the resistance to this idea is based on peoples addiction to quick fixes from well-marketed pharmaceutical products than anything else. Having been totally convinced by ones local authority that ones mental health issues are all a result of a lack of proper chemical balances in ones brains, being told that its really all about what you eat is .. unsavoury .. to those with a consumer-oriented mindset, who mostly just want to take a pill to solve problems while also being granted immunity from responsibility for ones dietary choices ...