"Babies are meant to crawl and adults were meant to walk."

As babies/children babies/children we learn to turn over on our belly, grab our toes, grip and pull ourselves up, cling, pull up, plank, push up, crawl, sit up, lunge, squat (like really deep), walk, run, etc. All with no pain or injury. 
Babies are meant to crawl and adults were meant to walk. You are right. But be honest, how much walking do you do? And is the walking you do the walking that is built off a foundation of crawling? 
Crawling is a developmental movement that ties everything about you together. In developing children, crawling activates and integrates the different parts of the brain. Through crawling, neural connections and pathways are established in the brain that allows the brain to become more efficient at communication between the left and right hemispheres. The better the brain can communicate and process information, the better the body moves. crawling also unites your sensory systems. It integrates your vestibular system (your balance system), your proprioceptive system (your sense of self in space, or your self-awareness system), and your visual system (your visual system). It can even improve your hand-eye coordination. Crawls are for all level clients, pregnant or looking to increase balance levels by adding plank board