TEPaul,
Different types of scratch golfers aren't taken into account either. One could become scratch driving it barely 200 with a pro level short game, or by being a long driving champ hitting it 390 with the short game touch of a bricklayer. There's always variation, all ratings (and pars) are just approximations. I don't even know how you'd attempt to rate something for a bogey player if you assume the whole range of possible ways there are to shoot bogey.
It reminds me of a tale from How To Play Your Best Golf All The Time by Tommy Armour (the first) He made a bet over someone who had never broken 90 that if he went around with him and told him what to do he could get him around in less than 90. He was having the guy tee off with fairway woods, lay up with 8 irons instead of hitting a fairway wood or long iron at a green, etc. Guy ended up going around in 79 shots!
Do we consider him a 20 handicapper since he'd never broken 90, or an 8 handicap based on its true potential when we are determining bogey rating? That is, do we assume the bogey golfer is stupid and hits driver to a par 4 with a sheer cliff on both sides of the fairway or do we assume he's smart and hits an iron off the tee for safety, even if it means he has to go at the green with a fairway wood? There's only so much you can do.