No skin in this argument but it should be mentioned that mother nature isn't after the same goals humans are when it comes to cannabis growth. The same can be said about professional bodybuilding. Bodybuilders undergo grueling lifting and cardio regimens that go far beyond "health and wellness" not to mention the diets which are so far beyond the realms of what normal folk could comprehend. They are hacking their genetics and using known biological sciences to tweak their physiques. Typically these are detrimental to health especially when you start talking about 4-5% bodyfat when they hit the stage or a pro powerlifter squatting over 1k pounds.
Mother nature isn't after the densest, stickiest, heaviest non seeded flowers on the plant that can possibly be grown. It's after a well rounded healthy plant that can bear offspring and start new progeny. Humans and mother nature aren't after the same things therefore humans use hacks that have been shown to better give us the outcome we desire.
Using the same old argument "mother nature knows best" or "why would God give cannabis plants leaves" to say defoliation techniques are wrong just aren't looking at this from the eyes of a person trying to "hack the plant" to produce more or different qualities from cannabis than mother nature intended. Sometimes the cost of stunted growth can easily be offset by increased yields especially if it means the larf will now become prime dense nugs after using a defol technique.
I agree, our goal is a subjective yield. The natural plant process essentially is to compete for light>reproduction although a lot of symbiosis exists.
I don't think people are ''hacking genetics''. We have a limited intelligence and what ever we can do with that intelligence is still within the rules of the game. We are only limited by our latest understanding and that is one of the gifts of being human, or curse, depending on what camp you are in. If a man builds up his body and dies as a result, can you sit there and say he got it wrong?. This is a question of ideology and your own perspective of the meaning of life. To him, he may have died young but HIS goal in life was complete.
When it comes to growing, we want yield, for most growers that is the top priority even over quality for some. Like I said, that is a subjective venture yet OBJECTIVELY some things are proven to work while other things are a grey area at best. Get any heavy defoliator to teach some newb for the first year. I would teach another newb with easy, repeatable techniques, I know for an absolute fact who will be yielding more. To use your weight lifting example as a comparison, heavy defoliation is like a man trying to put on extra muscle by starving himself of protein. We know biologically that you need a certain amount even just to live. It's why being vegan can be very dangerous if they don't know what they are doing. Defoliation is directly interfering with the process that puts on end weight, just like protein is to muscle mass. They may already have a substitute for proteign I don't know.. but what is a growers substitute for leaves?. The only answer to that is ''more leaves''. So it begs the obvious question, why remove them in the first place if they are clearly in a productive position. It's not like they can play dumb and say they had no idea leaves help things grow, cmon.. we all know that by now. They are simply lost in curiosity or ego land and have unlearned themselves of basic facts.
Heavy defoliation ''may'' have x/y/z positive effect but the problem is nobody can prove it nor can they give a guide to repeat it. To any new grower think about that. Why do something that can not be proven or repeated when you have many things you could be doing.. that you currently are not doing.. that are guaranteed to increase yield. Many long term defoliators who give guides will put in a disclaimer ''if you get it wrong yield will suffer''. No advice I can give to a new grower on proven techniques come with such a disclaimer, because they are so easy to follow step by step. They have pit falls to be careful of sure, but I know exactly where that line is so that they never have to get near it. That's a vital difference.
If a persons goal isn't yied, rather it is to play around then fair enough, I would recommend bonsai trees as they are far more fulfilling in that way. But I guess to fall into my own trap that is also subjective.