Isn't the logic of EDTO, that after a critical system failure the AOC approval requires an aircraft to land within the maximum diversion threshold of 3 hours?
So why would someone become airborne and suffer a critical system failure only to continue to the destination, further than the ETOPS diversion threshold?
I don't think anyone is suggesting that it's ok to continue past an enroute alternate (ERA) and fly further than the ETOPS/EDTO diversion threshold or rule distance (call it what you will!). However, it MIGHT be acceptable to continue past the CP/ETP for the nearest ERA and divert to the next ERA, if the more distant airfield is considered a better option and the operation is deemed safe. The distance to that airfield would obviously be one of the many factors that would need to be considered.