It's difficult to prove that something doesn't work or doesn't exist. There is massive anecdotal evidence that NLP works. Few studies have been done on particular aspects of NLP with mixed results. Milton Erickson was a strong influence on NLP's founders, but NLP includes aspects of many other disciplines as well. Many people use NLP as a form of self development.
People work perfectly to accomplish what they are currently accomplishing.
People already have all the resources they need. Behind every behavior is a positive intention. Every behavior is useful in some context. The meaning of a communication is the response you get. There is no such thing as failure.