Some of the dumps might be straight caregiver burnout. It does happen and it's pretty brutal when it does. When my mom went downhill her entire personality changed and she got really mean, it was horrible. I honestly wanted nothing to do with her by the time she finally landed in the home in crisis, I lost my 20s to caregiving. I do visit her at least once a week still, and I'm much happier with her relationship now that the responsibility is off my shoulders...but coming out the other end of that hell I do understand how people can just be done.
This is why having kids to look after you in old age is such a selfish pile of crap. I would NEVER wish on my kids what my mother put me through. Idealy they won't be having to do that, when I see them when I'm old I want it to be for a visit...not them driving me to errands, or cleaning up my bodily fluids, or investigating a halucination, or cleaning my home while they still have their own responsibilities. They are my children, not my future slaves. It's my job to plan for my eventual decline in abilities and that doesn't mean assuming my kids will pick up the slack. It means ensuring that I have the money to go into assisting living when I'm no longer able to take care of me and my home.
Your mother didn't "put you through" anything. That would be like blaming a child for what they "put you through." Families stick together even when it is hard. My grandma got mean, too. It sucked. But I knew that if we were caring for her, she was being taken care of by people who loved her, regardless. Just like she loved us when we were screaming little brats. Nursing homes are notorious for abuses of all sorts. Someone has to stay on top of things, constantly. When my mom was in the hospital one of the aides was stealing her pain meds, and no one would believe she hadn't gotten them. Unfortunately I was giving birth at the time and there was no one to stay with her. I'd never allow someone I love to be in that situation without someone to watch out for them. Recently in our sweet little town three teen workers were found guilty of sexually assaulting many of the women of the facility in which they worked. At another home they discover one of the coherent patients was having sex with 5 Alzheimer's patients.
While I don't work in a nursing facility, I do work with developmental disabilities. Many of the same issues crop up with our clients. So, yes, I do have a concept of residential care and the potential for abuse, neglect, etc.
My kids won't have to change our diapers, but they will always love us and watch out for us. Because that is the kind of people they are. There are crappy ungrateful children that dump, but I do agree with you. Some of the dumps are burnout. People need more support as caregivers.