I find that notion to be laughable, because my older daughter never crawled. She was obsessed with standing/walking at a very young age (she would scream until we helped her stand up, as young as 3 months old!). She also didn't roll over until she was nearly a year old - mostly because she HATED being face-down. Again, would scream until she threw up if we tried tummy time with her. So if your ped's theory is true, then my daughter would be a prime candidate for all kinds of problems!
Well, I'm here to tell you, my daughter gets straight A's in school (pretty easily), and has beautiful handwriting both in cursive and printing. At the age of 8, she is in a pre-pointe ballet class with girls who are 11 and 12, and she keeps up with them easily both in terms of strength, technical skill, and the ability to pick up choreography. She has also been in competitive cheerleading for several years, which would actually be a dangerous sport for someone with spatial relations issues! Fortunately, she has no spatial relations problems at all.
In my opinion, the reasons my daughter didn't roll over or crawl were entirely due to her personality. She is fairly stubborn, and extremely observant. She saw as a tiny baby that adults didn't crawl, therefore she was determined to walk! You could see the concentration and joy on her face as she stood up, and the frustration as she tried to walk and just didn't have the balance to do so at such a young age. But she sure wasn't about to crawl!
My younger daughter rolled, crawled, did all the "typical" stuff, and she is also smart as a whip, but is less neat in her handwriting, and is not as talented in dance as her sister. So... I'd say our family disproves the crawling theory! ;)