Yes I agree with you, but maybe I did not express my point with enough clarity. I mentioned this two species because they count as food of negligible caloric value (sidewalk amaranth is mostly useful because of the edible leaves). As far as I understand, human caloric needs at present population levels require the large scale conventional methods of production (including the Haber-Bosch process). But caloric needs aside, there are populations, which are not consuming enough greens or fruit, even when it grows in front of them. I have seen it in the (warm and tropical dry) countryside here, they think they have to eat lettuce, when they have lots of hibiscus plants growing in their garden. It turns out the leaves of hibiscus aren't just edible, but their nutritional value is similar lettuce (I suspect higher in Mg since it's a lot greener). The answer of some technologists to this problem is to grow more lettuce. Another plant that grows plentifully here certain months of the year is Ipomoea Triloba. I don't think anyone should try to produce them at scale following the conventional methods. In the case of cities I imagine there could be gardens with a synergistic diversity of plants, which try to keep a high total yield, but not a high yield of any specific plant.