Why does the US Army persist with the rank of SP4?

The US Army is the only branch that E-4 is not an NCO Junior leader including the Coast Guard. E-4’s as NCO’s builds leadership and Responsibilities. I served in the Marine Corps 10yrs and Army 8yrs and always gave my Spc-E-4’s more responsibility and duties and pushed them to the board. All the OTHER Branches promote their E-3’s on time and grade to NCO. Yes in the Marine Corps you will deploy with a ton of L/CPU’s and come back with a ton of Cpl’s but we in the Corps treat our young L/Cpl’s as leaders and train them to be Cpls by assigning them to Crew Chiefs in my old MOS AMTRAC’s and as Team Leaders. I would put any of my old L/Cpls against any Army Spc’s at the time, the Army has a training and leadership problem and needs to revamp their rank structure. All the other Military Branches can’t be wrong!

For a short period of time, I was laterally transferred from Staff Sergeant E-6 to Specialist 6. I had moved into a computer programmer position and no longer had troops to supervise. I made E-7 and was promoted to SFC. back supervising troops.
IMO, the idea of specialist was good at the time when we had a large standing force. Now, probably not so much.

My understanding was that if the Army made them CPLs, it would cut severely into troops available for fatigue and other details. NCOs cannot be on fatigue details. So in order to have enough soldiers for KP, area police, rock painting, etc. they kept Speedy 4. Otherwise, you would wear out your Privates.

Sp-4 full bird corporal.

I was a corporal as an MP, back in '86, because promotions were frozen, and I had been acting as Patrol Sergeant for months, with no end in sight. My Platoon Sergeant did the work to reward me. In 90, while I was MI, I was able to make a case that one my Specialists was acting as an NCO, leading an Analyst team, and I mean leading it. I got him his two stripes. He pulled 20 years. I don't know about now. But back then, if you believed in your troop, and were willing to put in the work, he could get that 2 stripes. It was just a matter of the leader being willing to put in the work to reward his troop, and recognize his effort.

I personally think that getting rid of the Spec 5 through Spec 7 ranks was a big mistake. Not everyone is cut out to be a leader. an NCO whether Corporal, Sergeant, Sgt 1st Class, 1st Sgt Sgt Maj is a leader. There are a lot of jobs in the military that require a great deal of technical expertise but do not
require leadership abilities. A senior specialist can still be as accountable as anyone else in their pay grades. There are a lot of folks who want to be a doer and not a leader. The current structure forces them to become a leader even if they are not a good fit for it. As a result a lot of good folks leave when they don't move up

A SP4 that's been selected, officially, to be a team leader should be laterally promoted to Corporal.

Actually they dropped the "Four" and left it at Specialist back in the mid 80's (1986/87). A Specialist doesn't have the NCO leadership authority of a Corporal. So you could be a team leader as a Specialist but lack authority to give a command (what some folks call orders). While stationed at Fort Drum, NY working in the 10th Personnel Service Company, Personnel Actions Branch, our section was without a Team Leader for an extended period of time, only the Section NCO (SSG) in place. Our Company Commander (MAJ/05) who was also the Adjutant General for the post decided to issue a Lateral Appointment for me to CPL/E4, based upon my abilities, MOS knowledge, and informal leadership qualities. No pay change, just the authority to direct duties and responsibilities. People say Rank has is privileges, but with that came responsibilities.

Just have to add that certain MOS's have special duties, knowledge, and training requirements that should be recoginized with the E4 Pay Grade, but not necessarily require the leadership Rank.

I was a 52E Prime Power Production Specialist operating a research reactor, SP6 promoted to SFC. I did not want to be a leader, I had worked hard to be specialized in nuclear and did not want the responsibilities associated with a leadership position and the distinct possibility I would be assigned to another specialty.

Sir, the Army attempted to differentiate between NCO and technicians long before the 1960s. The post-Civil War Army had ranks like Quartermaster Sergeant, Commissary Sergeant, Ordnance Sergeant Saddler Sergeant, Farrier, Principal Trumpeter, etc. By the end of WWI there were over 120 insignia of enlisted rank, most of which reflected the skills of the individual soldiers. When GA John Pershing became Chief of Staff of the Army after the war, he directed that all enlisted Soldiers wear chevrons that only showed their pay grades: Master Sergeant, Technical Sergeant, Staff Sergeant, Sergeant, Corporal. During WWII, the Technician system was devised, so that Soldiers with necessary skills could get paid more without being given NCO responsibilities for which they were not trained. Technician Third Grade (Tec3) was in the same pay grade as SSgt, a Tec4 was paid the same as a Sgt, and a Tec5 was paid the same as a Corp. The Technician system went away in 1948, and the Specialist system started in 1955. The SP9 and SP8 ranks were discontinued in 1968, SP7 went away in 1977, and SP6 and SP5 went away in 1985. Today's Army sends college graduates to basic training as SPC, as a recruiting incentive. Would you suggest that those E-4s be immediately given NCO rank and responsibility?