Because you can compare art-wise how a car such as Ferrari looks like to any sculpture or whatever, but if you'll start to compare the mechanical skills that make that car go to art skills that are required to make a sculpture.
It would be a false analogy, because those two things simply require different skills and knowledge - like comparing apples to oranges.
Again, it shouldn't matter on what forum you're on....because if you judge art on other basis than skills and art quality, you would end up saying that a stick man is totally better than a Vallejo painting because we are on the "stick-men" forum right now.
I actually wanted to ditch this discussion few posts ago, as i kinda understood where it's gonna lead but i'm simply so sick and tired (personally) of people stating that skills and art quality don't matter anymore, what matters is __________ (insert here whatever you want- imagination/story telling/originality/soul...etc).
It's my "elitist" personal view on art so i don't expect from anyone to actually agree with me.