But equally very black and white in some cases. A 737 climbing out of PH crossing a descending 737 inbound from SY may well climb above before the crossing point or pass in front/behind, but you don't just hope.
Separation Assurance is not possible or practised in Approach or Departures environment
So what do you call SIDs and STARs with complementary VNAVs?
Most arguments against Separation Assurance use ridiculous exaggerated examples, applied logically it has a place.