I think we are working too hard at this. The intent is that harry homeowner, standing in the yard with his orange cord, can get to a receptacle without climbing over the rail (accessible from grade), shoving the cord in a window/door, reaching or going up steps to reach a receptacle more than 6'6" above grade. If this is a low deck or patio, accessible from grade the receptacle on it will fulfill the requirement. IMHO
If it was screened in and you had to route the cord out a door ... no.
A more intertesting question is if the receptacle was under the deck, how high would the deck have to for the outlet be to be called "accessible"?
art 100
Accessible (as applied to equipment). Admitting close approach; not guarded by locked doors, elevation, or other effective means.
