My thoughts were the same in the beginning, but it's actually not a no-brainer. Canopy maintenance and training in general are way beyond other methods, imho. Also, you really have to know what you are doing. Brain involvement is definitely needed, at least in the beginning, to learn this form of art and plant cultivation. Hehe, please don't get me wrong—I still love the work and the 420scrog method.
At first, I kept asking myself: Why isn’t everyone growing like this? And: Why isn’t it done on an industrial scale?
Some possible reasons could be: Without restrictions regarding the number of plants or general growing space, other training techniques might be more suitable because they require less manual labor. Additionally, you can’t work with clones, since this method is done with autoflowers. (But could be done with photos aswell I guess, but they won't perform as good since 12hours of light during flower instead of 24hours).
But for private growers, especially those limited to a small number of plants, this method is wonderful. It’s also perfect for growmies who love high-performance gardening and pushing their plants to their limits.
Just my 2 cents. Happy to hear other opinions aswell.