I have 30 acres, some of it set aside as a biodiverse polyculture to help bend the cost curve on my animal keeping. In one of the most productive and forgiving climates here in the US. Zone 7b/8a, averaging about an inch of rainfall weekly (Not the most productive ground, i freely admit, too much clay in the soil). If you think that most people can set aside acres to feed their chickens, and that the clearing and maintenance of those acres is cost free, the annual taxes on that property inexpensive, you are again mistaken.Small farms and homes can make miniature versions of large containments of insects and plants for chicken feed purposes and reduce price with better nutrion.
I spent half a morning this weekend underbrushing another few hundred square feet with a small farm tractor, which has an up front cost, a maintenance cost, and of course a time cost.
Can people engineer an insect farm to suppliment their chicken's diet? Sure. It might even work. But its not a diet replacement, and its not balanced. Some can't even do that. Too hot here for a black fly larvae farm, for instance. 99 yesterday, true temp, not heat index. Sunday too. Today is a cool 97, predicted. There's a commercial cricket farm up the road - maybe I could do what they are doing, if I can figure out how they are doing it. An addition to my acres of weeds - but still not a diet replacement.
Look at the system as a whole - if you are producing your own chicken diet, you are a generalist, enjoying neither the efficiencies of scale or specialization enjoyed by large producers. If you are buying and mixing end products, you are paying layers of retail markup on all your ingredients. EIther way, greater expense.