But how do you know that "your" servers (the ones that would be assigned to serve you dinner in the MDR) aren't the ones delivering the room service? Or serving you in the Concierge lounge? As noted, the dinner servers do not just serve dinner, they have lots of other duties onboard. And it's quite likely that you may be on the receiving end of those services. Including cleaning up in the pool areas, serving drinks in the theater, lunch service at
Castaway Cay, quick serve at the pools and whatever else
DCL feels falls under their job description.
I doubt that anyone has entirely avoided places that the dinner servers work for the duration of the cruise. I know I couldn't skip my cookies from Flo's, or the ice cream station (yes, they clean up/stock there, also). I wouldn't even think about reducing/removing gratuities if I opted not to dine in the Main Dining Room for the whole cruise.
Plus, you've already paid how much for the cruise and you're quibbling about $24 for the gratuities?