I agree with Ian W.
In FIRs without an autotriangulation system there is very little support to the aircraft on guard frequencies they are just there as a (supposedly) quiet frequency on which someone in distress can call for assistance.
As far as I can see over most of the Western World emergencies involving IFR traffic will be handled by the main ATC frequencies. 121.5 tends therefore to be used as a standby universal frequency for loss of contact with ATC. Either by air traffic trying to contact someone or an aircraft asking for a relay. hardly an 'emergency 'I am not sure that over the Pacific or over most of Asia to SE Asia calling on 121.5 and expecting instant salvation will yield much in the way of tangible assistance. It might be useful in remote areas in terms of transmitting your last known position, to narrow down a search area. So outside of an area where it can be used to instantly fix your position and hand you over to an appropriate ATC unit, I cannot see that it is anything but a universal 'standby' frequency. I am not sure why the 'Guard Police' police it so vigorously. Nobody seems to object to an ELT in a hangar transmitting on 121.5 (very intrusive), why would they object to a practice PAN? 121.5 seems to have acquired a mythical status way beyond its possible usefulness. I cannot think of any real emergency situation where my first and most immediate action would be a broadcast on 121.5?
"YOUR ON PPRUNE!!""