I tried to find a good article summarising Michel's language teaching method.

This references his tapes: https://lukesmith.xyz/articles/learning-european-languages-m...

ChatGPT gave a reasonable looking answer to my prompt "Summarize what is special about how Michel Thomas teaches Language".

Maybe just another case of a highly intelligent person coming up with an "obvious" solution that is great: yet is not quite so obvious to others. He clearly was talented - but also he avoided explaining the rationale behind his method for years.