It was originally pitched as a scripted Survivor. To claim it is unrelated to that genre is to ignore both what it is and how it got there.
Actually, no it wasn't. In the first season DVD extras the idea was originally this, but they realized they needed more and came up with the mythos and mysteries of the island before they pitched it.
You're wrong about the filler too; there has been little to no filler so far, mostly because they did the smart thing at the beginning: they decided to end it at a specific place and knew when the ending was coming, so they made the story fit how many hours over the seasons they had.
Real Programs don't use shared text. Otherwise, how can they use functions for scratch space after they are finished calling them?