Just because some attribute exists in normal doses in most people, does not mean that it can exist in debilitating doses in a minority.
Of course, a big difference between imposter syndrome and the aforementioned illnesses is that imposter syndrome is not in the DSM-5. But if you look at the history of the DSM-5, you will notice that adding a new illness is a very slow and politicized process. And a large number of psychologists are treating it a bit to seriously for it to be just a "humble brag".
That doesnt mean everybody talking about their imposter syndrome would really classify as having it. Similarly people who checked webmd and now believe that they have cancer, also do not necessarily have cancer. That still doesnt mean that every cancer-sufferer is a fraud.
The variety I'm referring to is the one that comes from people like the one I originally responded to, who, by all accounts, is a successful functioning member of society. So, yeah, I think it's fair to say "claiming impostor syndrome is just describing a normal feeling" in contexts where the person is clearly not overwhelmed to the point of dysfunction.
Even if there is such a thing as actually crippling impostor syndrome, that's not what I see being brought up in these kinds of discussions.
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.
IMHO, you could leverage that uncomfortable feeling positively (e.g. seeking the right people to help you, etc as you said), negatively (e.g. give up) or in a beside-the-point way (bragging about the cup being half-full). None of this has really anything to do with acting maliciously/destructively like the article seems to suggest, though.
Imposter syndrome would involve feeling like all your past achievements were pure luck, you have no merit, and your collegues were going to find out.
There's nuance to the definition; people use the term like they use the term OCD. Not understanding what it actually means. Vanity.
There are extremely capable athletes with terrible ego problems and there are people that legitimately fall into death spirals. There are those that talk the talk but don't walk the walk, as well as those that quietly sweat away in their pursuit of mastery.
Lacking confidence in something, judging oneself, etc are just being human. Pretty much everyone goes through that. Sure, some might project confidence in the face of the unknown, but that's just one of many coping mechanisms we have. "Laughing to not cry", screaming in fear when startled by a spider, YOLO, panic lies, etc are other similar mechanisms where we do seemingly illogical things in response to the respective stimulus.
And of course, people are multidimensional and topics/disciplines are multidimensional. You can't possibly be great at everything, but most are certainly capable of getting very good at something (even if that something is being a generalist in software engineering - which is itself a form of specialization in the grand scheme of society). And you might experience impostor syndrome at work but still be one of those people that think they're above average drivers or some such. Or you might experience it and be confident about your looks. Etc.
When you consider that reality isn't a flat 2D grayscale spectrum, it seems fairly normal that one would experience discomfort with their lackings when compared against one of infinite arbitrary scales.