It depends. I think it’s definitely less common here because it just isn’t needed most of the time. Even a working class retiree should have a pension or 401k, social security, and some kind of savings from their life as a working adult.
To require the support of your children, you’d have to be unable to work, not entitled to substantial amounts of social security, not have paid into a retirement plan, and not have saved any money from when you did work.
I know a couple of people who support their parents, and they either spend their ENTIRE lives in poverty making sub-minimum wage (which is pretty uncommon), or they just straight up blew all their money because they assumed their kid would take care of them. I don’t have a lot of sympathy for the second category.
I think it varies a lot by the user. I think (hope) most people are just joking, but I’m sure we have a number of people who aren’t joking.
But also keep in mind we absolutely have propaganda bots and trolls here. They’re quite good at directing the hivemind, even without the assistance of complete loons.