Zoro is like roger and ace in that sense, they protect their crews like older brothers. While luffy needs to be protected by his crew.
It's been firmly established that luffy needs all the help he can get:
-luffy himself admitted that he can't do anything but fight.
-Ace and sabo had pointed out how troublesome luffy is and that he needs people to take care of him.
-mihawk addressing it's not strength is what dangerous about luffy it's his ability to draw allies to his cause.
Luffy has the strongest ability, but he's not the strongest, he's reckless and impulsive and always get into trouble, the straw hats spend the time skip improving themselves and getting stronger just to help him.
It's been firmly established that luffy needs all the help he can get:
-luffy himself admitted that he can't do anything but fight.
-Ace and sabo had pointed out how troublesome luffy is and that he needs people to take care of him.
-mihawk addressing it's not strength is what dangerous about luffy it's his ability to draw allies to his cause.
Luffy has the strongest ability, but he's not the strongest, he's reckless and impulsive and always get into trouble, the straw hats spend the time skip improving themselves and getting stronger just to help him.