There are a few different reasons why heads up poker is often called “heads up.”
The first reason is that in a heads up match, the two players are playing against each other alone. This means that the other players in the game are not involved and are not helping to make decisions or provide information.
The second reason is that in a heads up match, both players are playing all of their cards. This means that there is no room for mistakes or for the other player to help you out.
The third reason is that because both players are playing all of their cards, it becomes more important to be able to read your opponent’s behavior. If you can predict what he or she is going to do, you can make better decisions based on that information.
