You are right. Depending on when parents/grandparents make out their wills or change them, they often feel like they will lose control of their assets. I am sure it has happened in some way, otherwise, how would that rumor have started?
Illness does suck away the assets nowadays. Have you seen what the cost is for a private duty nurse if you have no insurance?
Of course those crazy things happen and it is too bad that someone can work their whole life, make a modest living and accumulate a modest amount of things, only to have it disappear. Most people would like to leave a little something for or to help their loved ones. A lot of folks also have no idea what it can take to make that happen or can't afford to put things in place to assure it.
Private duty anything is not affordable to the majority.