Creditors are calling. Without power of attorney, you'd have to go to court and ask to be named his legal guardian. You'd have to report to the court frequently, filing documents on how assets are performing and how much money is being spent. People who've been through this process say it's a nightmare. Having power of attorney is the way to avoid it.
Most people give it to their spouse or an adult child, a sibling, or a trusted friend.
It should be someone who is comfortable enough with his or her own finances to be able to handle yours. If you have no family members or friends whom you trust to make sound financial decisions, you can give power of attorney to your longtime accountant or attorney. Let's talk about them separately first. In some states both of these have been replaced by a single document called a medical directive. Hospitals and nursing homes often hand out forms, but it's better to have handled these matters beforehand.