Hi- let's look at the facts, Diamond never received 20% discount on all cruises...only a select group of specific dates/ships/itineraries...and primarily during the height of Pandemic and other travel issues causing low bookings.
Things change...
MSC is on the path to becoming the largest cruise line in the World and has the newest overall fleet period.
Diamond status never was like a AMEX Black Card...
Like most who travel extensively, all of the hotel, airline, rental car, etc Statuses have been diluted...this is nothing new nor unexpected.
No loyalty for me, just go with who provides what I want, when I want it, at a price I am willing to pay...
Enjoy your cruise!
Cheers!