"... development does not proceed by way of precedent..." - Public forum - Planning Advisory Service (PAS)

A recent appeal for an agricultural dwelling stated that: "it is important to note that development does not proceed by way of precedent" (See: http://www.pas.gov.uk/pas/aio/3477964) Well, I'm sure that I have seen planning decisions for similar rural agricultural dwellings view 'setting a precedent' as a major risk and is thus a valid reason for refusal. So does this Appeal result ... err , umm.. set a legal precedent which invalidates any future use of the 'setting a precedent' argument as a refusal reason for rural home applications ... or indeed as a refusal reason for ANY development?