I was a bottom shuffler, used both hands for all tasks, including writing, until I was well over 6, when I decided to start using my right hand for everything... and could read fluently at 3, have always been extremely well co-ordinated, have neat handwriting, was always good at sport and gymnastics. Of course I can crawl if I want to... I obviously didn't want to when I was a baby - probably because I am very hypermobile. In other words, there may well have been physical reasons for not choosing to crawl to get around, but there most certainly weren't long term neurological or physical reasons.
Ds2 was late-ish crawling (10 months) and walking (17 months) but is likewise advanced now with his gross motor skills, extremely advanced with fine motor skills and motor planning, and could read at age 3. Like me, he is hypermobile and loves to w-sit. Ds1 has slightly low muscle tone, is extremely hypermobile and needed to be taught not just how to crawl but how to get from lying to sitting, sitting to standing, climb stairs, walk, etc, etc, etc... He could read at age 3, was an early writer (can't draw for toffee, but could form letters correctly when only 2 or 3 - he's good with symbols, just not good with pictures...), is possibly slightly hyperlexic (was happily reading, eg, Roald Dahl books to himself at 3), can play the piano, ride a bike, swim... he does not have natural motor planning skills, however - needs to be taught fairly simple physical tasks and relies on his phenomenal memory and lack of any problem with balance, etc, to learn how to do things that other children could work out in seconds without realising they had to think about it at all. He is phenomenally good with numbers. Basically, what is supposedly instinctive, he needed to be given active teaching to learn, but what is supposed to need active tuition (eg reading, writing, arithmetic) he has a natural instinct for. Whilst he is highly verbal and imaginative, he is also far less strategic than his brother - he doesn't really do thinking ahead, so dislikes board games. Maybe an issue with "higher order" thinking? Or is it called executive functioning, or something???? But only certain aspects of it, since he has a brilliant short, medium and long-term memory...
Observing my children and how they are developing, I have decided to take so-called experts views on, eg, crawling, with an enormous pinch of salt. Of course not crawling can indicate a peculiarity in development that can mean something long-term, but WHAT that actually means is not predictable, nor is it preventable even if it can be ameliorated. Yes, if your child doesn't seem to have found any means of moving around by, say, a year old, teaching it to crawl is possible. Sticking the poor mite on its stomach for extended periods of time from an early age and leaving it to cry piteously because some interfering idiot says it is good for it and you MUST do it every day for at least a few minutes regardless of the child's reaction will NOT ensure it learns to crawl, or even develop the muscles it needs to do it if it has low muscle tone and a motor planning problem - more effective intervention is needed, rather than needless cruelty at an age when the baby is too young to understand why you are torturing it in that way... in my experience...