If by "this whole thing about imposter syndrome" you are referring to people talking about imposter syndrome the way your parent comment talked about it, than yeah I agree completly: its just a humble brag, nothing else.

I originally understood your comment to mean impostor syndrome is never used in a valid way. I have seen these statements being made about mental health disorders, including very serious once like depression. I think they can be really damaging, since they convince people not to seek help. This is why I disagreed.