My nephew rolled around the house like a bowling ball, never crawled, then ran instead of walking, and has no problems of any kind (he's now 26). My son, age 27, never crawled, flopped on his back like a flipped-over turtle that couldn't get back on its feet, then figured out how to walk at age 14 months and never stopped. That boy is now 6'3", graduated from a very demanding technical college with a near-perfect GPA, and is successfully employed as an audio engineer and sound technician.
Leave the random lady out of your equations altogether. She's probably got a hundred other old wives' tales she could tell you, like don't look at a mouse when you're pregnant or your baby will be born with whiskers and a mouse nose.
I do think that in certain cases, where a baby is born with muscle weakness or cerebral palsy, or certain disabilities, that crawling exercises and therapy can be one tool in the therapist's program to help stimulate the brain or strengthen the baby's body or help with balance.
But for a child who does not have muscular weaknesses or balance issues or significant developmental delays in many areas, there are nearly as many ways to crawl/run/roll/hop/slither/jump or otherwise get from point A to point B as there are babies.
Developmental delays, sensory issues and learning difficulties don't occur because the baby skipped chapter 2 in the "how to be a baby" book and therefore didn't get the "now you have to crawl" instructions.