Why should a back splice be avoided when reeving a block and tackle system?

A back splice should be avoided when reeving a block and tackle system because it can create a thicker section in the line that may not pass smoothly through the pulleys, leading to increased friction and potential binding. This can adversely affect the efficiency of the system and may result in wear or damage to both the rope and the blocks. Additionally, a back splice can reduce the overall strength and integrity of the rope, compromising safety during operation.