They didn't kill the golden goose. Other places implemented tax benefits to encourage film making. That is why so much filming is done in Canada, New Zealand, and various Central European nations. If anything, the golden goose flew away. As a counterpoint: What do you think California and LA area local gov'ts should have done differently?
Not keep adding to the taxes, expenses, and red tape? Work to address the outrageous cost of living in CA that indirectly drives expenses for labor? It's a million and one policies that all contribute to how running a labor heavy business in CA is increasingly challenging (bearing in mind that those factors matter less to a software shop or Apple).
As I mentioned elsewhere in the thread, CA's labor-pool's own hostility to the film industry (via strikes) also played a big role. They gave the studios the finger, then are surprised that the studios took their ball and went elsewhere.