Polygraphs are based on principles beyond junk science. Any person who has been in a cult organization and has successfully exited can testify to convincing yourself something happened or is true even if the evidence is overwhelmingly the opposite, even under a polygraph. People are not reliable sources of fact, period. They are an interrogation technique based on scare tactic strategy to get people to confess to something regardless of if it is true or not.

Polygraphs only do one thing, enable lazy investigation into claims of fact. That's why police love them so much.