Edit: or if you meant the grandparent claims not to be a doomer but is pessimistic about something, I don't see the contradiction. It's more like "I don't generally like sweet things, but this cake is nice". Where's the contradiction?
It's a bunch of people endlessly frustrated they never self actualized, hurling this frustration onto whatever random topic comes about.
Constant whining about anything new or any change in the world...because of course everything was better in the past and anything new is worse.
But things weren't better back then. These people were just happier in the past, because when you're young, the future is a horizon of boundless opportunity.
As you get old you realize that opportunity is over for you. So for the non-self actualized, it leads to shaking your fist at the clouds, telling everyone to get off your lawn, couching those emotions under supposed concern for abstract concepts like "societal moral fabric" instead of admitting you didn't achieve what you hoped for yourself.
The entire mood of the internet over the past 20 years has simply been a reflection of its biggest cohort (millennials) going through life.