O
Perhaps some people learned crap, and some people didn’t.
no one would say kickboxing doesn’t work, but that doesn’t mean every gym that offers a kickboxing class of some sort is going to teach you to be a good fighter.
I wonder what your coach defined as competing at a high level.
possibly the most accomplished point fighter seems to have adapted to full contact in karate combat just fine. He may never rise to the level of a UFC champion, but if he cross trained with some ground fighting, he’d likely be at least competitive in the big name MMA organizations.
bottom line is that several big names in MMA trained karate their whole lives, continued to train karate while competing in MMA and themselves attribute much of their success to karate, so I find it amazing how randoms on the internet know more about their training background, and how they fought than they did.