I get where you are coming from, but I think the best point in this somewhat rambly essay is that it is fine to come out and talk about how to deal with these odd mental effects, especially when they are keeping us from getting work done.
Usually when people begin kicking up a dust, the solution is to stop kicking– in this case I think that means to avoid making claims, and focus instead on doing great work!
When they are sincere, sure. But increasingly they are becoming like the thin girl forever talking about how she feels fat (or, I suppose, the not thin girl declaring that anyone thinner is anorexic). The Dunning–Kruger thing is referenced so frequently on here and other technology sites that it is like the attempt at a great equalizer: People aren't better than me, and the only way they can think they are is the Dunning–Kruger effect.
It is some sort of race to the bottom / lowest common denominator equalization thing. I'm not saying that the feeling of inadequacy at times isn't real, but it is becoming a badge and measure of superiority.