As a cook that is taller than most, I can maximize my work area greatly by using my height.
I usually prep on my line on a small cutting board inbetween orders. When an order pops out or when I get totally swamped I can conveniently store my cutting board/prep work on top of the microwave/work area and resume when my tickets are gone.(Needless to say you shouldnt do this with raw proteins)
I can also store backup supplies on top of my work area so that means I make less cooler/dry storage runs.
When in the cooler I don't need to leave and go find a stepladder to reach the mushrooms stacked way up up up in the cooler.
The down side is that when our cooler is overstocked with boxes or prep carts, so I have to suck in my gut and pretend like im playing twister to get in and get out.
With all due respect that strikes me as a ludicrous question. I can point to a number of chefs that exceed the average height and weight of the majority and their talents and abilities match their size. This is cooking not pro football the only time size becomes an issue is when they are obese and their size becomes a liability in the kitchen, then they move out front where it's safer :)
I definitely think being in good physical condition helps in the kitchen. As far as height goes, I haven't noticed a difference. But yes, physical fitness is important for any job that involves manual labour, I try to stay in top physical condition.
I am certain of this:
I have seen people of all heights, weights, ages, and experience levels be ground up and smashed to bits by our facility, and have seen a few individuals across the same demographic cope.
Aside from this narrow, formulaic criteria, there is a lot more to look at when considering who is going to let you down and who isn't.