I had the exact same reaction as you but vitriolic, had to take a step back and treat it like a research exercise (in another reply)

Re: "but they're happy" x obviously ridiculous, it hit me 10 minutes in, if we're going off 99% happy, it's absolutely absurd - then the conclusion is we should give everyone down's syndrome.

My initial snap reaction was it must be trolling. But it can't be, if you're looking to stir the pot you don't do it on the 6 comment non-technical post on the second page.

Which kinda makes it more disturbing, to me, because it goes beyond someone not understanding. It's some sort of weird active misunderstanding, like, seeing fun heart-warming Downs syndrome sibling videos on social media is enough for one to assume it's net-good, somehow.