It's literally nothing more than a result on a test, but because that test is trying to reflect your own inherent behaviors, there's value in using it as a set of ideas for introspection
I think if you have folks take the test and you do enough interviews/assessments, there are likely commonalities and themes. which is why folks will find it accurate.
Because in a lot of situations, it IS accurate. And a lot of behaviors often == "types". Though it's usually good for reflecting and introspection, less about predicting futures or choices and such.
I feel like you can get away with doing that, assuming you buy into it, because your sign is supposed to affect your personality. It's at least internally consistent.