I'm a cb 3 skiller on OSRS. I've had about four nightmares so far accidently completing a quest and suddenly being CB 9, or accidently attacking someone and then levelling up a combat skill. It was horrible. At that moment you know you can never go back and you're extremly frustrated.
Ah that would be very scary, sad, and frustrating indeed!
I wish that players have an option to toggle off skills that they don't want xp in, like they can still train but instead of getting any xp drops, they won't get anything.