I don't know but two things come to mind:
1) The natural sebum in your hair is supposed to protect your hair (assuming you brush or comb every day and have short hair, which many people have)
2) The acid mantle of the scalp should be maintained at a certain level. Perhaps these sites think conditioning the scalp would upset the acid balance.
Personally, I've been using diluted conditioner all over my hair, including the scalp, for years, with no harm.
Bookmarks