I think some fields have certain canonical methods which are often impractical, but foundational. And the "real" methods used in practice can, with work, be see

I think some fields have certain canonical methods which are often impractical, but foundational. And the "real" methods used in practice can, with work, be seen as an approximation or limit in some case. Understanding that perspective is useful in being able to reason about the trade-offs of different approaches. In cryptography, the equivalent is the one-time pad. It has trade-offs which make it unavailable for many uses, but by some measures it is literally perfect and the only thing which can be perfect.