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.
OP's example is the wrong way to do it as they water plants in soil, there are plenty of hydroponic towers that you can 3d print and what they do is allow you to have hydroponics (growing plants in water) with very little space requirement so that works great in small gardens or appartment balconies.
Sure. But still, why a tower? Even at their best, towers are just shelves that require more floorspace.
A tower design like in the OP's picture allows separating the humid root-space from the general work environment which has some practical advantages and I guess also lowers the risk of fungal infections of the roots.