Board Thread:Theories and Speculation/@comment-34661853-20181111160651/@comment-32685487-20181111171253

Kabuto used Hashirama's DNA to repair Sasuke's heart. Being gifted some Hag chakra boosted the awakening process, as without it he would have awakened it years down the line just like how Madara did. Naruto did not gain any flesh/dna at all, he only was gifted some Hag chakra too. It's really just that simple.