Sorry, but you are incorrect. While the studios on location at MGM Studios Florida never produced any massive hits there were dozens of TV shows and movie filming sessions going on throughout the early years and prior to it being a theme park. Although many flopped and were under the Disney name, it was still a WORKING Studio.
Ernest Saves Christmas
Adventure's in Wonderland
Mickey Mouse Club
Teen Win Lose or Draw
Mortal Kombat: Conquest
Out of the Box
Marvin's Room
Tarzan's Epic Adventures
Big Bag
Kermit's Swamp Years
And lots of various filming from production in the Central Florida area as well. I recall House on Haunted Hill being partially filmed at Islands of Adventure for the opening theme park scene as you may know, but when they needed some interior set shooting done the studios at Universal were occupied at the time, so the went and used a stage at Disney. There are tons of post production companies that rent and use spaces on studio lots.
While for the most part, like Universal its a shell of its former self with what they do for tv and film production, it WAS a studio.
In the 1980s Florida was being looked at to be the new filming location for many productions because some things about it are cheaper than filming in Calofornia. After California Florida is still one of the biggest states for filming in the country.
Disney did not spend all that money and time to build soundstages and facilities for a fake studio. If they were just doing what we have now than they would not of needed all the facilities behind the park.