It is currently very hard to kill a user in the end due to /warp and combat logging (logging off before you die). Also, it is easy to create a macro that makes you invincible (ex. if health < 2 then /spawn).

A combat logger should be added to prevent the use of certain commands (such as /warp, /spawn, /sg join, etc) and to prevent you from logging off when you have recently taken or given damage to another player. For example, if I were to PvP someone and be close to death and log off, a "ghost player" would spawn in my place after I log off. If that ghost player were to be killed before despawning my stuff would drop on the ground.

The addition of a combat logger would allow for a fair PvP experience which is what Andrew is trying to achieve with the End.

 

It seems like Andrew and the Server Admins have gone out of their way to provide a hardcore PvP environment in the End world by removing commands such as /vanish, /tpa, /fly, etc. However, /warp was not removed due to the fact that it would take far to long to walk back to the main portal in the end world in order to get back to the main world. Even though many features and commands were removed to create a PvP environment, /warp seems like a huge loop hole, and a combat logger is the only practical fix I could think of it fix it.

 

You asked how would it harm me if someone combat logged. Taken from what I said above, the End was meant to be a competitive PvP world where you risk your things in order to make money. If I can go into the End knowing that there is very little chance of me getting killed then that isn't very competitive.

While combat logging doesn't harm anyone's character, it does not go along with the overall intention of the End.