Give me one Robin brute strength feat. What has she done without her DF that indicates she is stronger than normal.Yes she is.
The point is that Zoro and Sanji are still vastly stronger than Robin, but if she can beat them by snapping their neck, what's stopping her from doing the same to those 4?
let me explain.
Zoro and sanji are maybe 1 teir up.
So lets say Robins strength = 1
and Zoro/Sanji strength =2
With her df she can use her power to manipulate her 1 strenght to over come their 2
DF + Strength = 3
Zoro/Sanji Strenght = 2
3>2
But higher ups like you mentioned arent enough to be bested by a +2 from a DF