ClearTarget() isn’t a secure command, nor does it require a hardware event to trigger. This allows for a variety of automation.
Examples: Apparently ClearTarget() isn't a secure command
It can be abused in PvP so you will never get juked. Your kick will only be used if something is being casted.
There are also various other ways it can be used to automatically prevent you from casting spells when you’re not supposed to cast them:
They added more in-game restrictions this week: