Anecdotally, I think pesticides become 'necessary' when a specific farm desires greater than a particular density of crop. Sure, the collective can achieve sufficient production with less use of these chemicals however when a farm is at a point where their plants are touching each other then serious pesticides are required if they wish to increase their yield further without pests becoming a catastrophic risk to the entire operation. If only we could all agree to just grow 'enough' instead of growing as much as science allows...