You should go ahead and diss the Toyota Productions System and Lean Enterprise as well.
Just because most American companies don't know how to deploy an initiative does not negate its validity. ISSO is about standardizing your processes (standardized work), and Six Sigma is about reducing variation caused defects in processes. DMAIC is simply the application of the Scientific method to problem solving. However, these programs are deployed as empty slogans and cheesy signs in the foyer.
I personally have overseen multiple millions of $$ in cost savings at companies from Life Sciences to Welding rod manufacturers, and everything in between using Lean and Six Sigma tools. These programs always fail because of the incompetence of management, in spite of the best guidance money can buy. Many companies don't want to make the hard decisions required to fix their problems.
Don’t know or assume they already know it all and if the idea had been worth anything they would’ve already thought of it.