That was kind of the point of the book.
Terry seems to have taken the phrase 'the magic of Hollywood' and said - what if there was real magic there? What if we had no choice but to make movies because the movie magic was making us do it.
The book is an homage to everything to do with the cinema on our planet, but given a Discworld twist.
It asks questions like - why on earth would anyone eat popcorn? What is it about someone who stands in front of a camera for a fairly short time that makes them into some sort of god? And why will people do almost anything just to be associated with the whole film making industry?
So, to go back to your question - the reason it seemed so familiar was because it was supposed to be.
“Men never commit evil so fully and joyfully as when they do it for religious convictions.” – Blaise Pascal