Just because ICAO (all hail!) says we can do it .... Use common sense, think of the Swiss cheese and all those holes in it and also never assume and all that jazz!
Agree 100% and you will probably agree that in practice the callsign is used more often than ICAO say it is necessary. There are a few notables who use it less also!
However, one can not complain when people do what the book says.
Regards,
DFC