I think the faded ones may be less common.
i use to get them, the faded ones spawned the same as the pure blacks, just no one wanted them, everyone wanted the pure blacks.
so the shaggy and pale blacks where just killed off or not even tamed.
to get totally technical there are 4 colors of black horses.
pure black with a short haired mane.
pure black with a shaggy mane.
light black with a short haired mane.
light black with a shaggy mane.
i have all of them on one of my characters on sonoma for comparison purposes.
and no, its not OCD!
i just like to have everything.
everything in its place.
all lined up, in their place.
perfectly in line, all neat and orderly and in their place.