It's the same group of problems as Moorabbin with everyone funneling in via Carrum and GMH approach points when coming in from anywhere including the training area.
It's not uncommon to see half a dozen aircraft over Carrum all reporting their position as Carrum with anything up to 2 miles or more between them. If the radio is busy you may not get a call in until the 3 mile mark if you aren't quick on the PTT.
The problems then continue as the tower often tries to work out who is actually number one.
Tower: XXX, you are number one.
VH-ZZZ: But tower, we are ahead of XXX
XXX: We just paseed ZZZ
Tower: Ok XXX you are now number one
and it goes on from there... half the time you might never even see the aircraft.
If it's proven experience in the US that this problem can be solved by eliminating approach points, then it is worth considering and CASA is obliged to do this.