The ‘lean tools’ movement is directly in conflict with the beliefs of the architect of the TPS. Taiichi Ohno asserted that method must not be codified:

While most companies focused on stimulating sales, Mr. Ohno believed just-in-time was a manufacturing advantage for Toyota. And for many years, he would not allow anything to be recorded about it. He claimed it was because improvement is never-ending – and by writing it down, the process would become crystallized.

Ohno 1988 pxi [foreword]

To codify method is to impede understanding, thus lessening the chance that people will challenge any underlying preconceptions they may hold. Even the tools protagonists recognise that the focus on tools was misguided, but rationalised the mistake.