Force, like velocity, is a vector quantity with both magnitude and direction. The farther away from vertical the angle goes, the higher the magnitude of the tension force must also increase for the diagonal to remain capable of holding the same force. When a load hangs from a vertical, a single force needs to pull with at least the same force as the weight of what needs to be held. If more forces are used to hold the load, then each force only needs to hold part of the total weight. So, for example, if you need to hold 100 N and you have 4 forces to hold it, each force must hold at least 25 N because it can distribute the weight.