Why would anyone give such sweeping authority to another person?

One answer is convenience. If you are buying or selling assets and do not wish to appear in person to close the transaction, you may take advantage of a power of attorney. Another important reason to use power of attorney is to prepare for situations when you may not be able to act on your own behalf due to absence or incapacity. Such a disability may be temporary, for example, due to travel, accident, or illness, or it may be permanent.

If you do not have a power of attorney and become unable to manage your personal or business affairs, it may become necessary for a court to appoint one or more people to act for you. People appointed in this manner are referred to as guardians, conservators, or committees, depending upon your local state law. If a court proceeding, sometimes known as intervention, is needed, you may not have the ability to choose the person who will act for you. Few people want to be subject to a public proceeding in this manner so being proactive to create the appropriate document to avoid this is important. A power of attorney allows you to choose who will act for you and defines his or her authority and its limits, if any. In some instances, greater security against having a guardianship imposed on you may be achieved by you also creating a revocable living trust.