The Three Tiers of Hip Hop

At the advent of Hip Hop, before the age of the internet, two tiers existed: mainstream and underground. With the age of the internet, I believed that the two tiers have become three. These three tiers are mainstream, sub-mainstream and underground. For examples, Lil Wayne and Kanye West fall under mainstream, Childish Gambino and Macklemore fall under sub-mainstream and Immortal Technique and Cannibal Ox.