We built an in-law apt onto our house and my mother lived with us for 25 yrs, until the moment she passed. It worked out really well for all of us. When my kids were little, she helped out, and always had an open door so they could go in and watch a movie with her, or she’d cook them something, etc. As she aged she had all her needs taken care of, and we were able to even do hospice at home with two of us being nurses. So many people have said how lucky she was! I’d say we all were.
My DD will probably be taking over the apt once we fix it up a little, while she saves to buy something of her own. That will work out well, too. In some other countries, it’s normal for multi-generational families to live together and care for eachother. I think here, in modern times, there was a lot of availability of affordable apartments and land and such, so it wasn’t a necessity for most families, but our economics are rapidly changing now. I’d say if people get along fairly well, and it’s well thought-out, it can be a good thing.
I have an elderly friend who lives alone in a rent-controlled apartment. I saw her last night, in fact. And she is terribly lonely there, and afraid to open up to her caregivers about how much her mobility has declined, because she’s afraid they’ll make her go to a nursing home. She told me that sometimes she just cries.

We also see a lot of problems in the hospital when people fall, or mess up their medications, and a medical crisis occurs. (Saw this recently where someone was over anti-coagulated because they took their medications incorrectly and a critical neurological event occurred. No one in their family realized what was happening until there was an incident.)
In a lot of ways my life was easier because my mother was right there, off my living room, so I could stay on top of everything. That wasn’t always the case. Before she moved in with us I’d have to travel over an hour in the opposite direction to get to her, sometimes after working an overnight shift (and having to be back the same night), if there was a problem, and it seemed to happen a lot. I had to send police to her house before for a well-person check when I couldn’t get a hold of her. Some of the locals who “helped” her from time to time didn’t always have her best interest at heart and actually caused some problems, so I worried a lot. All that changed for the better when she came to live with me.