It's not new - it's how things have been for the last 10 years or so. All CASA has done is clarify things in AIP.
Actually it is a CHANGE from what was instigated in NAS. However the major problem is that CASA (through their ignorance of the intent of original procedure) thought it was a CLARIFICATION and failed as a result to conduct any sort of risk assessment or safety case in support of what is now a CHANGE.
In the great majority of cases the MULTICOM would only be used at low levels and good airmanship would suggest that once en-route, the area frequency would be monitored. Discussion about its use at higher altitudes is irrelevant to this discussion.
So what about the strip that is on or close to an area frequency boundary??