it exists and its not necessarily due to breakage. i think the hemline depends on the way your nape grows if you do not cut it.
as you can see i have no hair in the center of my nape. any hair that grows there is very sparse yet the sides are dense.
when i wear my hair straight and down the lack of hair in the middle manifest itself as a gap in the hair. depending on the way i comb and the lighting it it is not visible.
you can see it really well here. i think it looks better when curled
this is why i prefer a blunt cut so the the crown hairs cover the disparity at the nape