I don't think it was cargo-culting in the case of that fab. A fab isn't like your mother's ham, which she cut in half because her mother cut it in half, only to

I don't think it was cargo-culting in the case of that fab. A fab isn't like your mother's ham, which she cut in half because her mother cut it in half, only to find out that her mother had a small oven. A fab is like that tricky piece of code that has a comment on every line, but instead of one function it's 20,000 lines of that. On top of that, it takes several weeks before you know if your wafer came out okay. So when you duplicate your fab, the last thing you want to do is add more potential problems. Think of it like using a software library; you don't go rebuild the library each time you use it, you just copy it into your project. Sure, there's unnecessary piping, but you don't care. If you cared you'd write your own library in assembly language and it would be a shining example of efficiency and understanding. But maybe you just want to solve your problem and ship.