I'm not going to disagree with the main thrust of the argument. But I do think you're overstating it and using it to have a go at other social attitudes.
1) A big part of that increase in agricultural productivity from one person feeding two people to feeding 100 people is Promethean energy use rather than Smithsian productivity via specialisation. It can't be done without the increase in energy usage facilitated by cheap and plentiful fossil fuels. Yes, going against that specialisation is a bad idea, but the system is still broken and solutions still have to be found to create a sustainable version of late 20th century agriculture.
2) Just because there's a section of the Green, eco-aware movement that is into the stupidity of knitting yogurt into yurts doesn't mean that the Green, eco-aware movement can be dismissed totally as universally stupid. Repeating that too much begins to look like techno-utopian denialism and an attempt to smear attempts to recognise a real problem and look for real solutions to it.
Which is to say we need a Green movement that embraces technology, specialism and capitalism. But it still needs to be Green.