Celebration is owned by Disney, the land was shaved from the original Disney property though I believe. Golden Oaks can be argued about being in EPCOT. Logically there would have been an area such as that in EPCOT, if not originally, then in the years to come. Personally, I don't agree with the whole Golden Oaks thing, but that is just me.
EPCOTs vision has been taken from a concept city to the entire property. You just have to look past the original vision. Walt's death changed everything, to the point that the Florida Project was almost not built. Many of us have to look past the original concepts, and even the orignal stuff that started out in 1971. I know I do. Let me compare the current incarnation to a concept that is years old, the planned community. It has many of the features, the living space which are hotels, resorts, and campgrounds. The activities and shopping which would be theme parks, water parks, golfing, water sports, Disney Springs. Then we come to infrastructure and I will include fire departments, hospital (celebration), refuse, recycling, water, roads, transportation, power. You have government in Reedy Creek, and even TDO. The entire property is just like a planned community instead of a eyesore jumble that an actual town or city is.
We should also keep in mind that concepts change over time, they evolve many many times. Walt wanted a place where people could work, live and play. Granted the living is temporary, work as in all cities involves commuting, and playing, well yes it happens on Disney property by guests, locals and employees alike.