I had the filet with BBQ sauce back in 2010 and paid using DDP. But Cali Grill has a regularly changing seasonal menu, items come and go all the time. They always offer a filet, just the sauce and accompaniments keep changing. Currently it is with onions, steak sauce and mac-n-cheese,
https://www.wdwmagic.com/dining/california-grill/menus.htm
Yes, the dining plan has made some menus appeal to lowest common denominator and also made some places use lower quality ingredients, but some of those changes are also due to general cost-cutting. But at the signature places I don't think DDP has as much effect as the general cost-cutting and also many dishes regularly change at signature level restaurants anyway with the seasons.