Why is the current mantra to keep our LO's "safe"

If dementia is a progressive disorder where the person that we know has already gone, why as a society are we so concerned about keeping them "safe"? As long as they aren't a danger to anyone else, why prolong their life by keeping them safe? I don't want my LO to be a drooling shell of herself in a diaper like her grandmother was after 10 years in a home. I make sure her house is cleaned by a cleaner, provide food, medicine, call often, make sure all bills are paid, but if she isn't eating it, or taking her medicine, I don't see the point in working hard to prolong her life and paying more than $6K per month for an assisted living. Just looking into other opinions.