Because- generally, it is much easier with a hone to go too far and cut through the cylinder coating, rendering it useless.
If removing transfer from the piston melting and galling onto the cylinder wall, there is no fear of creating some kind of elliptical bore through hand sanding- as you are merely removing the soft transferred extra coating back to the original cylinder lining. With a hone it is relatively easy to cut the transfer off and the lining, especially around port openings.
CAREFUL and proper use of a ball hone might be considered the safest option- but best to have some practice on a scrap cylinder before you start.
I agree to a certain degree if you hone the cylinder for long time you could possibly break through the plated surface and the design of hone used makes a difference, but to just say DON'T hone the cylinder is a statement that is incorrect, being as the manufacturers hone the cylinders during manufacture.
Using a ball hone as apposed to a 3 legged stone hone is the way to go, but also you haven't stated that a ball hone should be rotated in both directions to clean up both vertical edges of the transfer ports......
Also glaze busting is totally different from removing piston material from cylinder walls, plus why do most saw porters use hones to after porting cylinders either new or used???
I wouldn't hone a new cylinder kit unless the cylinder has been ported, but honing is the very very last stage of porting to clean up any slight possible roughness left