The whole premise of a lie-detector test is that they are marketed to end user and the public at large as being both accurate and "scientific." That they yield results better than chance isn't particularly relevant: they are not what the sellers and users of them claim they are. The conclusions drawn from the readings of the machines are only loosely based on anything scientific and depend heavily on the interviewer's own personal biases. Yet they determine the fate of people's lives all the time.
Polygraphs are almost certainly not reliable enough to convict someone on, but it's not admissible in court. That doesn't mean it can't be used to help coerce a confession or help lead an investigation. And the fact that you won't face up to the extraordinary amount of evidence showing that it can be useful suggests stubborn ignorance on your behalf.
So can tarot cards, and magic 8 balls. polygraphs are bullshit pseudoscience and 100% interchangeable with any other fake bullshit when combined with a experienced examiner and an ignorant/gullible interviewee
Glossing over or attempting to detract from the grossly negative consequences doesn't automatically arrive at the conclusion that it's resultantly a "good" thing.
[0] - https://www.innocenceproject.org/polygraph-tests-contribute-...
>Notwithstanding the limitations of the quality of the empirical research and the limited ability to generalize to real-world settings, we conclude that in populations of examinees such as those represented in the polygraph research literature, untrained in countermeasures, specific-incident polygraph tests can discriminate lying from truth telling at rates well above chance, though well below perfection.
https://www.nap.edu/read/10420/chapter/2#4
Although it is not a silver bullet, it certainly has its applications, especially if the person being interviewed believes it works. Thus, the polygraph test makes sense in questioning sex offenders, for example:
https://onlinelibrary.wiley.com/doi/abs/10.1348/135532508X29...