He said staying in konoha made him pretty weak.
Now that I think about it,when he was in team 7,Naruto was pretty stronger than him.it was only when he left konoha that he surpassed naruto.
And if u'd Notice,when naruto was in konoha,he was weak,his saving grace was jiraiya dying,which made him learn Sennin Modo.
The war came,he had to get stronger.If Not for bee teaching him how to control Kurama,he wouldn't have been so strong.
The war also help him gain BM.
So in essence,if jiraiya didn't die,and the war didn't come,naruto would have remained in the same level as konoha 11.So Infact sasuke was not to be blamed for leaving konoha
Naruto is My Favourite character,so don't start.