I guess that I never really listened to Cobain as a Lead Guitarist.
What I heard was a Genius in Harmonic Substitution who mastered the art of co-mingling some dissonance with melodic phrases. Through a combination of substituting harmony between his Vocals and guitar tonality is what created his unique sound. His gift with Accenting and chordal placement gave life to the lyrics with creative songwriting that changed an era (even if using common type progressions that others had used many times before).
Many will create music through variations with these progressions, but few will change it,............. Overnight.