Not just BN Centre either! Yesterday morning out of YSSY at 0415, not exactly a busy time for conflicting traffic enroute (except for the arriving internationals inbound from flight levels) ML centre forbid direct tracking until I got to 45nm SY when queried the controller tipped me that I was OCTA and I could do what I wanted.
Nobody but me flying at that time in that airspace but costs my company an extra 0.2 on the flight for no benefit in safety.
Pointless really.