How is Apple watch made out of stainless steel be any different from a normal watch made out of stainless steel? If one buys a Ferrari, one wouldn't expect its paint job to be scratch proof.
The Ferrari is painted, the watch is not. I've already saw on the net that the watch even at the early stages getting some scratch complaints.
Apple has touted that they tweaked the alloy, but to what degree, I have no idea. The fact remains SS does scuff up, and while a watch can be largely protected since its on your wrist, a phone is more vulnerable.