It's grim because it's mostly a made up, self-centered, apocalyptic view of the world - great in one's youth and now fallen. I think your other instinct - 'maybe I'm just getting old' is truer, and better - that doesn't have to be nearly as grim as the coping-mechanism-cum-manifesto in the GP comment would have you believe.
Alternatively, notice how detractors to a well thought-out argument that attempts to distill decades of history into a single comment within a larger thread, immediately devolve into flailing insults rather than offering a compelling counter-narrative.
Sure, pvg's bite-sized nugget of McWisdom holds generally true for any topic covering a span of time and wrapped in the cloak of biological aging, but notice how it also does nothing to provide sustenance in the form of tangible examples, counter-arguments, or advice. It's convenient, sure, but hardly nourishing.
I don't think you misrepresenting the period in bombastic terms for effect provides sustenance or requires counter-arguments because it's just you misrepresenting the period in bombastic terms for effect. I think the advice of not taking a sequence of Manichean tropes and slogans too much to heart remains pretty useful!