Anyone know why MGM doesn't freeplay match with other casinos?

Recently took a trip to Biloxi which had several different types of properties there to play at. While doing a freeplay match round of visits, when I went to the local MGM property the lady at the service desk said they no longer match freeplay, even with direct competitors like Caesars. Anyone know exactly why? Is there a master list online of casinos that match vs ones that refuse?

Did freeplay matching used to be a common thing at MGM properties? Last time I saw that was a one-off at Resorts World LV in the first few months they opened, and when they looked at my offer, they shorted the FP and lowballed my room. Never as a routine kind of thing.