What 1988 actually taught, and what people got wrong about it
Rick Roufus was not outclassed by Changpuek Kiatsongrit. He had a blind spot that was invisible from inside his own rulebook, which is a different and more interesting problem.
The story is usually told as a morality tale: American kickboxing thought it was good, met real Muay Thai, and found out. That version is satisfying and mostly wrong.
Rick Roufus was one of the best American full-contact fighters of his generation and he was ahead early. On the hands he was the better fighter, and the scorecards said so for two rounds. Then the accumulated damage to his lead leg passed the point where it would hold weight, and the fight ended in a way that had nothing to do with who was the superior striker.
The useful reading is not that he was overrated. It is that his ruleset had never required him to defend a low kick, because under American full-contact rules nobody is permitted to throw one. He had no reason to develop checking and so had not. That is not a personal failing — it is what his rulebook asked of him.
Which makes the fight the clearest demonstration on record of something this site keeps arguing: a ruleset does not merely permit techniques. It determines which skills a fighter ever builds, and leaves the rest as blind spots that are invisible from inside the code. The only way to find them is to fight under a different one.
The American scene absorbed the lesson and moved toward adopting the low kick, and the gym Duke Roufus built now teaches leg kicks as a foundation. That is about as complete a correction as a scene can make.