Single persons with no children obviously do not have all the issues of married couples, those with children, or even those in committed relationships. However, if they care what happens to their estate when they die, they still need a Will.
If a single person in Maryland dies without a Will, the entire probate estate goes to the parents, if living. There are many circumstances where this is not the desired result (tax implications or Medicaid issues for the parents).
If no parent is living, then the probate estate goes to the siblings (or the children of any then deceased sibling). If there are no parents or siblings living, the probate estate goes to the grandparents or their descendants (aunts, uncles, or cousins of the deceased single person).
A simple Will listing the people and/or charities whom you do wish to receive your estate, modest or otherwise, resolves all of these issues and allows you to decide these matters.