Vertical farming, the best solution to support an ever growing population or just a scam?
IMHO it has a lot of potential but not being able to grow grains really is something that should be tackled sooner rather than later. But I could see this being used by self sustaining communities to provide lots of food while using very little space. And it's technically more environmentally friendly than just using vast stretches of land to produce the same amount of food.
A lot of mushroom farms put mushie blocks on racks, but that's because it's just kinda the best way to optimize for the limited space available in a lot of cases. After all, you have to control the humidity, temps, and possible contam vectors so that you maximize your harvest. If you're curious, look up mossy creek mushrooms on youtube, think they have a tour of their growing setup.