That seems like an oversimplification, outside looking in for me, but there’s no way a single dimension could ever adequately describe an item of clothing - my sister and wife have similar sized waists, but something tight round the posterior on my wife would be baggy on my sister.
a.k.a makes the clothes fit anything but skin-tight because the pockets need space so the clothes have to be wider-cut
That seems like an oversimplification, outside looking in for me, but there’s no way a single dimension could ever adequately describe an item of clothing - my sister and wife have similar sized waists, but something tight round the posterior on my wife would be baggy on my sister.