If you have a link to further reading, I'd like to continue researching the subject.
The closest thing to a credible scientific study I found on defoliation was in regards to cotton crops, and the general consensus was that there was still a heated debate on it's ability to actually "increase" yield.
Time must also be considered. If we remove vegetation, which causes stress, time to recover is required. If we provide time to recover, it extends the grow cycle. If we extend the grow cycle, our production per day average may be lower.
We could also consider quality of the final product and bud size, however, technically those are separate variables from yield. If defoliation results in a higher quality of final product, but a smaller yield, then defoliation is simply a personal preference.
And down the rabbit hole it goes