I don't think anyone is questioning the need for leaders and a chain of command. I think the question is the officer/enlisted divide.

A new 21 year old 2nd Lieutenant outranks a veteran sergeant when they may have less practical experience than even a junior enlisted like an E 3 with a year of service.

There's no good reason you couldn't have everyone enlist as a private and rise through the ranks from rifleman to platoon leader without the artificial line of "guys with shiny stuff on their collars" vs "guys with stripes."