I don't really remember for sure but I also think that MSC assign more staff to ensure that boarding during the cruise is easy for YC. They seemed to have staff everywhere where a line could form to ensure that YC passengers didn't had to wait!
That was worth much on our Mediterranean cruise this summer because it was superhot and very nice to cut all lines! People not in the YC seemed less happy about it!
Some people said things, to staff not to us, and some just looked but why should I care, I had paid for that perk!