Why was the ‘coup de grace’ removed from the core rules ?

@West_Thijs_23 Why was the ‘coup de grace’ removed from the core rules ? The coup de grace was absorbed by the unconscious and petrified conditions and by the death save rules.

— Jeremy Crawford (@JeremyECrawford) May 3, 2016

@JeremyECrawford Makes sense, but how to deal with sleeping baddies (Can they survive if they have enough hitpoints?) 1/2

— Thijs (@West_Thijs_23) May 4, 2016

A sleeper is under the effects of the unconscious condition. It says what happens to an unconscious target. #DnD https://t.co/AnbsHnfale

— Jeremy Crawford (@JeremyECrawford) May 9, 2016