It is beneficial, just not from a financial aspect.
With Reedy Creek, Disney doesn't need to worry about whether local politicians will approve expansions or meet the needs of the Walt Disney World complex since the local government is purely serving Disney.
If you take a look at Disneyland in California, Disney is going up against Anaheim and Orange County councils on a pretty routine basis to get new things built.
They would be worse off in the same sense that a child who doesn't get to eat cookies for dinner is worse off: they didn't get a thing that they really wanted. And in the same way, a child isn't harmed by denying them cookies for dinner.
With Reedy Creek, Disney doesn't need to worry about whether local politicians will approve expansions or meet the needs of the Walt Disney World complex since the local government is purely serving Disney.
If you take a look at Disneyland in California, Disney is going up against Anaheim and Orange County councils on a pretty routine basis to get new things built.