Technicolor movies were made the same way, "Gone with the Wind" to name one.
Then came the Kodachrome and Ektachrome color films with simpler cameras and projectors and Technicolor went away. Now the old color movies are mostly faded and gone, but I bet the Technicolor stock still remains if it was on safety film. Of course you need a Technicolor projector to view it.
Sounds just like digital vs film debate some are having today!