The Marine Corps does quite nicely with every E4 being a corporal and every E5 being a sergeant. Every Marine is a rifleman and if you’re not leadership material then you need to find another occupation before you hit the NCO ranks.
In case you hadn't noticed, the Army and USMC are two very different organizations with two very different missions. When I was commissioned as an Armor lieutenant, I seem to recall USMC lieutenants in my Armor Officer Basic Course. When I transitioned to the MP Corps and attended the MP Officer Advanced Course, lo and behold...there were Marine Captains in my class!...many of the courses were being taught by Army NCOs.
The USMC is a far more streamlined, efficient force by design, but it also relies on the Army (and Navy) to absorb a lot of the overhead so it can remain lean and efficient. As an example, in our OBC we had communications class learning the (at the time relatively new) SINGCARS radio system and associated comsec equipment. The class was taught by a couple Signal Corps NCOs who did a fine enough job, but I would argue that I, as an Army Armor lieutenant, and my peers who were USMC Armor lieutenants would have all been better served had the class been taught by a SPC7 who had spent their ENTIRE career doing nothing but servicing radios and COMSEC equipment, than a SFC who had spent PART of his career working with radios and the other part training soldiers to fire their weapons, dig fighting positions, inspecting uniforms, etc.
The Marine Corps is much more of an elite, shock troop, assault force and is normally MUCH smaller than the Army. The Army can afford to have two enlisted tracks, as they have had since the War Between the States, off-and-on. I left as a Spec/6 and wasn’t great NCO material, but I wasn’t in the combat arms. Far from it.