KP is sending our DS to Basic Airborne School soon at the end of his sophomore year. The mid who went a month before him got the "Honor Graduate". So, it's not true that KP can't prepare you well for a career in the US Army.
I don't disagree with the underlying premise but that is a bit of a leap of logic.
Success in a three week class that is run by and primarily used by the Army but is in truth a DoD school does not automatically equate to being prepared well for a career in the US Army. Being the Honor Graduate from Airborne School is a worthy achievement, no slight there, but jump school is only one task and it is an individual task. KP will not give you much if any of the technical knowledge one needs unless you are going to a ship (SWO, USCG cutters or NOAA). Being prepared well to be a career military officer means that you have the capacity to learn and grow into a leader of hundreds and possibly thousands of SSAMCG.
I think like any commissioning source KP "CAN" prepare you well for any branch of service but whether or not it actually does depends on what you do with your time and the lessons learned. Whether or not KP prepares one well to be an Officer in the US Military first depends on what you think makes a good military officer. If you choose the wrong mentor or example you won't really learn much useful. Don't be swayed by someones rank or position. I have met O6s and FGOs that I thought were useless and I wouldn't piss on if they were on fire. I've also met junior enlisted that I would follow into the proverbial gates of hell with a bucket of water.
I would sum up my military education at KP as follows:
1. I learned more what NOT to be like at KP than what to be like by observing both the Commandants staff and the assigned active duty liaisons.
2. I learned a LOT through Sea-year lessons and experiences being taught and guided by ship's officers. How to lead and guide someone who can say screw you if they want to with minimal repercussions. That takes a real leader.
3. Observing and listening to the enlisted around me as an ENS/LTJG. There are some things typical in officer-dom that do not exist in the enlisted world. How can you lead them if you don't understand them.
4. Reading and absorbing books and stories by and about other Officers and leaders. I highly recommend "Its your Ship" by CDR Michael Abrashoff, "Steel my Soldiers hearts" by COL David Hackworth, and "Execution, the discipline of getting things done" by Larry Bossidy and Ram Charan
I got some nice FITREPs from senior officers and flag officers, I was selected for command twice at LT and LCDR and as a LT I was put in charge of LCDRs and CDRs but I didn't take any of that to mean I was really a good officer or not. It just meant I fit a mold well enough and proved more proficient in particular tasks at a particular time.
The most important thing to me was when one of my PO1s made Chief at his next unit and he asked me to come and pin one of his anchors on his uniform. That was my single proudest moment as a Naval Officer.