You are right in the practical applications, but its still not bullshit. The facts are what they are and knowing them can be useful, although it isn't necessary as many successful photographers can attest to. The science and math is supplementary, but shouldn't restrict the way that you work. When im out photographing, im not thinking of all that nonsense, and quite often im not when im printing or developing either, its just useful to understand the process and how your materials function in order to deconstruct the mysteries of it at times.