It gives your trusted DPOA the right to make decisions instead of you.
Depending on your level of paranoia, it is probably not a good idea to use an heir.
The other missing ingredient, that everyone must have, is a doctor who is working for YOU, rather than the government or an insurance company.
We had a doctor for ten years, before I got divorced. This guy is great, and still practices up here, but I'm not his patient. Could I name him? I don't have medical insurance, but I still use the group. There's the one lady, who is a nurse practioner that I've been seeing, too.
My level of paranoia is on high alert. There's money involved.