variations in body proportions, yes, but if you need a stem that small, it's pretty clear the frame is way too big. humans dont vary that much unless a deformity has occurred.

how's the seat tube length?

just flip it for something that'll be comfortable. no big deal.

where's that picture of the steamroller with a zero reach stem? looked like a tin can coming out of the headtube and riser bars on top like antlers.