Yes EPIRBs are a great thing,for a boat/ship IMO,and are required by law on passenger vessels
in a sinking as they auto activate & deploy or other at sea emergencies.
I can just see the USCG deploying for some guy that turns his on in a non test period and relates to the flashing strobe as some 60's disco thing or lost his boat in a multi mooring area in the FL Keys! As said its is a dangerous thing and lives are at stake to do a false search or recovery!
I think they have their place and proper marker equipment,SS,Markers,Glow sticks,Noise makers are far less technical,and costly and if used properly get you out of a bind if you and your top crew plan your dive and dive your plan! other wise you don't or they don't belong out there=IMO!