On one hand, there seems to be a society-wide stress engendered by the global events of the last several years, which could explain more and more people have anxiety about many things, including themselves.
On the other, sure, when a concept such as impostor syndrome becomes widespread, more people are going to try to weigh themselves against it, and try to appear on the "right side" of it. Thus, in almost in a humblebrag manner, dismiss flaws as self-doubt or lack of confidence.
> The delusion is broken! There's only going to be improvement!
Not everyone has the same productive inner critic. Some people can be self-critical to the point of paralysis, to the extent of wallowing doubt. To self-loathing and absolute defeatism. Look at the increases in mental illness, addiction, and worse in society. Some inner critics kill, whether a person's potential, or their actual life.
Now, the OP uses a generic one-size-fits-all, vapidly positive self-help soothing solution, which might not help a lot of people. And so it becomes easy to dismiss, and to dismiss impostor syndrome as simply an excuse. But I'm just reminding you that not everyone is able to step up to challenges in the same way. Not everyone has a healthy growth mindset to overcome one's mental blockades. Some do lose themselves in the valley of despair, and could benefit from self-affirmation. Maybe just not the basic content-written approach in the OP.