Jonkstor. What would be the problem with harmonising with the simple proven FAA system?
The problems are the same as they were during the implementation of NAS. IFR aircraft are using the CTAF for amateur approach control to arrange separation with other IFR flights. This is required because the "approach-service-down-to-1200agl" bit of the simple proven FAA system wasn't implemented anywhere during the time of NAS, and now exists, without any obvious disasters, in only a few locations.
Drunk with pride at resolving IFR issues said pilots extend their skillsets to separation with VFR, and this f@$knitted proposal from CASA is backing that trend.