I think that is true, but not the whole truth (staying on theme). It is an interrogation, but it isn’t meant, or likely, to catch a trained, hardened spy or someone that can stand up to interrogations. It is to attempt to find if there is information that would make someone a bad candidate for a clearance, the same as the general background check is doing. If you are in massive debt, you are at much higher risk of being bribed. If you are cheating on your wife, and attempt to hide it during your polygraph, you are at much higher risk of being blackmailed.

It isn’t going to “catch” everyone but it is another way to reveal people with vulnerabilities that could be exploited. I think the real issue is people that “fail” the polygraph, since it isn’t actually a lie detector in any sense. It would be better if they just considered it a polygraph assisted interrogation.