It would be lovely if every adult felt as you do, that it is our responsibility as adults and parents to take our own affairs and organize, plan ahead, save the exact right amount of money required for our future disabilities... Even if we don't make enough money to pay for our decline, we can make it clear to our children what we want and most especially what we don't want in terms of health care at end of life, who we want to have make decisions, etc. Just that part would be FABULOUS.
I think you are right in large part. I also feel differently: that people do have some obligation to care for a parent or other family member to our best extent, because not everyone is so organized. Or someone had a stroke early and didn't have time to put everything in place. Or your parent worked in social justice and never made much money. Or ... there are lots of circumstances that are hard to anticipate.