Hence why I said "primer." I'd never post up a blog post as the definitive word on any subject.
I'll have to ground truth those wiki sources when I have more time. It is pretty clear that 1) our bodies contain shit tons of collagen; 2) glycine is critically important for collagen synthesis and several other metabolic functions; and 3) while technically non-essential, our ability to synthesize glycine from serine is woefully inadequate and dietary supplementation is advisable for optimum health.
http://www.ias.ac.in/article/fulltex...4/06/0853-0872
Considering that gelatin is cheap and either improves what you add it to or is unnoticeable, I don't see much of a reason not to use it liberally.