NOT Naruto, It's Sasuke who borrow powers. Naruto did learn jutsus at his own and managed to avoid Kurama, that's really impressive.
Do you know what is the meaning of borrow, look below.
borrow
ˈbɒrəʊ/
verb
1.
take and use (something belonging to someone else) with the intention of returning it.
"he had*borrowed*a car*from*one of his colleagues"
synonyms:take,*take for oneself,*help oneself to,*use as one's own,*abscond with,*carry off
you use for temporarily or parmenatly a thing or items from someone that still alive but still you must returned the items back to his owners even at one time he want to give it to you forever, the owner word you cant denied it because you are just a borrower like naruto and kurama.
But I dont said that kurama not letting naruto using his power forever, but the fact is kurama is alive and on his own being unlike sharigan, that is mean kurama is alive to give naruto chakra or help. The different that blurring the borrowing act is that kurama is befriend with naruto today unlike before when they still an enemy. It like before you dont befriend with your library operator and you need a permission to borrow a book or else get out but if you have befriend with the operator, you even dont need any permission
