If it is inflammatory it is probably because the initial statement was too sweeping - my flying in CAS is mostly done in a slightly bigger aircraft than fits into the GA category and of course there it is all done on GPS, in the UK I often fly outside CAS in an aircraft without GPS, I seem to manage this quite successfully, even inside CAS in the UK it can still be done, though you may need to turn down some clearances, thus disproving the premiss that to do so is ALMOST impossible, if the statement had said it was "almost impossible for flying across Europe in CAS" that would have got a different reaction!