It's interesting, I think more neurotypicals "stim" than they would think. I find that all throughout my life I have been always, almost constantly at all times, moving various parts of my body in repetitive ways. Tapping or twitching feet, legs or hands; muscles or moving in small sequences, again and again, without realising it usually. For example as I write I twitch my left foot, then some muscles near the knee of my left leg, while moving my right foot up and down in small "tapping" motions in between the left leg's movements. It's unconcious, and if I try to stay still I can do it, but trying to stop it, once I realise what I'm doing, feels wrong. It's comforting. I'm not saying it's the same as autistic stimming or try and claim that as something that doesn't "belong" to me, but it's a behaviour I always have done and will likely always do.
I think my movements are "on the spectrum" if you like, of stimming movements. I would suspect many neurotypicals have the same experiences, they just aren't as dramatic as most autistic stimming.
I also remember as a child rocking a lot and finding it very comforting. At what level do people think this is "pathological"? It seems unfair to characterise a movement that harms no one and comforts the mover, as "bad".