I must say stretching is extremely important. It's a lesson I've only recently learned, and since I've been stretching carefully everyday (+ other muscle work) my weak foot and wrist are feeling much better (I've only gotten serious about fitness the last couple of years, thus my intense research on recomposition). My GF was basically disabled from her tight shoulder muscles (she's a gardener, and had torn her rotator cuff, etc.). When she finally got her X-ray it was totally healed, as you'd expect, but that didn't prevent her from feeling disabled. So she performed the basic stretches she was given during physical therapy and she healed herself in 6 months (she had been limited physically for almost 2 years). It really drove home to me that stretching is the foundation of health and strength, not some relatively unimportant, slightly helpful method. So now both her and I are commited to fitness and we're gaining muscle and strength by making sure our muscles and stretched and flexible.
So I think my health/muscle building knowledge is finally complete. I think of it as a pyramid:
Low-fat vegan diet for optimal healing potential
Stretching for muscle balance and flexibility
Intense but safe muscle work
It is important to realize that one of the reasons children heal quickly is that puberty slowly lengthens the bones, which automatically stretches the muscles. That's why some bodybuilders are into extreme stretching, they are trying to similate puberty.