You are very correct. My son just graduated from basic combat training, with minimal hand to hand training. They save the good stuff for special forces. He also has a buddy that went into the Marines with a TKD back ground, and was very good. During hell week, when they free for all, his comment was that everything you were taught before boot camp went out the window, when you had many guys on you all at once.
Fortunately training doesn't end with Basic. Everyone keeps training for their entire careers. There is a lot more specialized training after Basic.
Special Forces is a totally different deal, although I would LOVE to see their FM or Guidance.