The particular asymmetric training I conducted was in accordance with UK CAA expectations. It was not asymmetric circuits for example. The UK CAA has quite a good reputation for safe practice. But given Australia's recent accident history, sure, discouraging or forbidding may be appropriate at this time.
I don't have any accidents to relate. But perhaps these TEM practises would have helped the accidents above?
Has the examiner placed feet to physically prevent wrong rudder input? Will the examiner take control immediately the safe outcome is no longer assured? Will the examiner discontinue the exercise if performance isn't immediately satisfactory for any reason at all? Has the examiner quietly reviewed the intended flightpath to prevent loss of SA if distracted? Is there any terrain ahead or abeam the aircraft? If not day VMC are there two independent attitude indicators in plain sight, and is the aircraft at relatively high speed and low power, to mitigate yaw & roll, and are the height buffers even bigger than normal?
Apologies to Leadsled & other experienced pilots - this kind of thing is already done by many experienced pilots and I don't mean to imply otherwise. But obviously not all pilots.