((@McT)) Your point started off with "farmers shouldn't grow what they know they can't sell", and I did say (though it got eaten, unlike the grapes) that, yes, it would be nice to do something useful to the supply. That led to the (shorter in the original) pondering about biofuels.
But, the thing is, at the level of the farmer it's often totally out of their hands what they can do about anything in periods shorter than a year (and, for orchard, vineyard, etc farmers, over multiple (even many) years). What do you think you could tell the ones who would have planted barley if they'd have known the wet/heat profile across the growing season was more appropriate for that than what they actually did plant..? If they get only half of what they expect, for their effort, their anticipated margins may turn negative. They may fill their hoppers with grain, but of inferior quality and make less return for it. Everything might go perfect, except that they've bet on the same answer as too many other farmers, and there's that glut that (again) makes any operating margin dissappear. And this is for those who can be flexible, one season to the next. Growing vines won't be a bed of roses. (And even growing beds of roses isn't!)
The rest of what you're going on about (the economic politics of political economies) isn't difficult to understand (as to how difficult it is to do!), but you don't help matters when you appear to blame those that are as much a victim of circumstance (and cannot directly, or even possibly indirectly, help the differently needy) when trying to make a larger scale point.
(Interestingly, I made sure the last message of mine was paste-buffered, in case it 504ed on posting. It did, I prepared to paste it all again and then saw that it had been received even though the post-post page had failed to generate. So I guess I hit it just right, timewise..?) ((Happened again. Pasting again after both me and the server have had a bit of sleep..))