The importance of immersive study
The first paragraph of the introduction tries to explain how anthropology is different than other disciplines which study human behaviour in some way. The main point made is that much anthropological study is done by researchers living amongst and often as part of the community that they study, and often for long periods of time. This is, in my view, not just important for anthropological study: in many areas there are a great deal of subtleties which are easily missed, ignored, or assumed away. Many researchers in areas such as medical science will apply textbook formulas and methods, lacking full understanding of the theory behind them, the proofs of underlying theorems, and how the methods depend on underlying assumptions. This can lead to naive errors and false conclusions, but is scarily commonplace in my view.