"Here's a crazy idea, how about everyone just eats their damn vegetables and we get 2kg from 2kg of food instead of 1kg from 2kg of food?"
EXACTLY! It is far more advantageous, never mind economical, to eat the direct product of the agriculture rather than cross-feed the harvest to an animal to husband...just to, eventually, eat said animal. And yet, every time this type of question appears for discussion the same thing happens: the Westerners come out and vehemently defend their high meat intake diets to the point that even when under duress from economic, social or environmental pressures, all that gets offhandedly dismissed as the ideas of 'crackpots', 'treehuggers', 'veggie nutjobs' or (nowadays) 'socialist schemers'.
So what is going on?
Let us attempt to examine this question from a perspective of a dispassionate observer: We are witnessing the outcome of centuries of socio-economic and peer pressure.
For hundreds, if not thousands, of years, meat was taken in by the masses on a limited basis. Livestock, or game animals, were either expensive to raise/harvest or outright banned. For example, in the Middle Ages the wild animals on the King's or your lord's land were not accessible to you, the lowly surf occupying said land - they belonged to the master. As such, the master made the rules and the rules were that you were not allowed to hunt for food on his land except by express permission, anything else was poaching in the eyes of the law. So poor surfs made do with diets high in cereals and vegetables while meat was the costly luxury afforded during good times, special occasions or by the high classes.
With the rise of the middle class in the early 20th century, the desire to acquire some of the trappings of wealth that had so long eluded them was high on the personal agenda. From jewelry, originally worn as a visible display of the wealth of the upper classes, to exotic foods previously too expensive to partake in, the middle class sought what was previously denied. Meats, and a diet high in such, was one such luxury still in vogue even in the late 19th century: the wealthy would hold lavish dinners for guests featuring plenty of meats, some featuring exotic types from far-off locales, as a display of their ability to treat the guest to only the finest. The upcoming middle class wanted to have a taste of that 'good life'.
And so meat consumption exploded during the early-middle part of the 20th century in Western cultures, as the individual society grew in political and economic strength. War-torn Europe had years of hardship where meat was a rare luxury, doled out when available by ration, but as the economies of Europe were rebuilt the production and consumption of meat also skyrocketed to way beyond prewar years.
So what we are fighting here is more than simple diet plans - we are fighting people's adverse reaction to equating 'no meat' = 'poor' ("poor" in term of either economic or social standing). Low-meat diets are for the 'lower / poorer countries', not for Westerners who can afford and deserve common access to such (historically luxurious) foodstuffs (as the article implies). This is a mindset - Westerners have been told for the past 20 years that a more richy varied diet, high in vegetables and grains, would benefit their overall health yet many Westerners still cling to a high fat, high meat intake diet due to being ingrained by the society's stigma against such a 'menial' diet. A high meat diet is for 'real men', and is still a show of wealth - at a BBQ, a host providing a large tray of steaks is seen as a generous provider to their guests, only the best.