I had heard that too. I guess it does give you an idea of the rhythm of adult upright movement -- a bit like pedalling on a tag-along type bike extension thingy gives you the idea of bike balance. (Which I gather it does for at least some kids although sadly Leon is not yet at the stage of providing any pedalling assistance. ;) )

I think someone (Mum? my aunt? can't remember now) made me nervous by muttering darkly about bandy legs etc etc; and I've seen some debate about whether crawling-before-walking is important or not & have no idea what would influence that, really. But he shoves up on his legs without any adult encouragement at all so I shall assume he knows what his body can do.