Professors teaching such courses at the graduate level primarily intend them to benefit students doing active research in the field. There's an extraordinary emphasis on mathematical derivations to show how one idea leads to another. This is intended to both (1) provide insight into why methods work—though less rigorous and more intuitive approaches frequently exist and are discovered by the less robotic students, and (2) give students practice in the mathematical gymnastics needed to publish in the field. The benefit to a practitioner, let alone an interested outsider, will likely be small.

An analogy might be to consider whether a course on type inference and Hindley-Milner offered by a computer science department would benefit someone interested in learning Haskell.