> Of course, the key question is: is all else equal? Organic farming does permit some other chemicals, and has a wide range of other impacts, including yields etc. So it's possible that organic farming is net negative for human welfare.

It is a given that organic is a net negative. Non-organic allows everything organic plus everything organic prohibits. We might need to reform non-organic in some cases, but those doesn't mean we need the arbitrary restrictions of organic.