You're making a whole lot of assumptions here. Let's break some things down.
1- "I guess them raising us as children, changing our diapers, making sacrifices for us etc. doesn't count for any kind of paying it forward because..... me, me, me, me, me."
No, it counts for nothing. That's your job as a parent. You're not required to have children in most countries I know of. If you sign up for having a child, you sign up to raise them to a point where they're self-sufficient (within reason). If you can't or won't be able to do that, you can have them removed from your custody. Doing the bare minimum (feeding, clothing, educating, and not abusing) a child is your job when you decide to become a parent. Are families complex? Are there lots of communication issued? Of course. But that's not what this article is about.
2- "The other issue is that as our parents and relatives get older their mental condition declines." My mother was verbally and physically abusive since I was a toddler. My father is a (semi)functioning alcoholic with a heart of gold and a lifetime of his own abuses. This is who they are. This is a misdirection. Some people become shit as they get older. Others were always terrible. If my parents behavior worsened as they got older, they never had any gratitude to start with because of their behavior when they were younger.
3- "Very few people are beyond redemption". What. The. Fuck? Who cares? Why is it my job to fix them? What if they don't WANT redemption. What if you tell them, time and time again, "your behavior is hurtful and ruining my desire to have a relationship with you. You need to get help. You need to work on your problems" and they refuse? Of course this is often about mental health issues. That's the basis of mental health! That your state of mind is causing you problems in your relationships and ability to function in the world. I believe many (some?) people are able to overcome their issues. I also believe many people don't care or recognize what they're doing. There's plenty of personality disorders that include "I'm not the problem, the world is the problem" as part of their diagnostic behavior.
TL;dr- My experience runs entirely contrary to yours. What a strange beautiful world we live in. Opinions aren't facts.