Yeah, it introduces a degree and level of complexity which is bound to confuse things. For the operator. For the Coast Guard. For other boats.
Some see DSC as a blessing. I'm not a fancier, since I doubt if ANYONE out there will have the same understanding as others. Multiple users of complex systems not having a common understanding is a recipe for disaster.
It needn't be so messy, but it is. Mixed signals from ITU, local jurisdictions, manufacturers, users, and "testers". Clearly, from the video even the USCG has only a foggy notion -- mostly incorrect -- of DSC operation.
Even the MMSI number itself isn't inviolable: the U.S.-only MMSI number issued by Boat U.S. and by others is different from and not as useful as the FCC-issued MMSI number recognized by the ITU. Now, the UK is joining the mess. What a clusterf..k (to use a technical military term).
Basically, DSC is just like the SELCALL system used by aircraft. That system works very well. If only the basic DSC function(s) were used -- at least in the beginning until everyone understands and is comfortable with the system -- it mightn't be so misunderstood.
Let's see now, how do I initiate or respond to a 'group call' ?
Yes , youre quite right, DSC should have been solely used for Distress ALerts. Its all the "routine " DSC stuff thats complicates the system. It should have just been the red button and nothing else as was orginally forseen under GMDSS. But ship owners got into the fray and saw benefits and then the usual design by commitee followed.
BTW what the USCG are advocating , ie seperate MMSI for handhelds cannot be done with the FCC issued MMSIs, but then the USCG are spectacularly badly informed about DSC.
As you say its a clusterF*&k or a compete SNAFU.