One problem is that the job of the dramaturg and the process of dramaturgy are frequently conflated. Even Routledge's Big Book of Dramaturgy concentrates mainly on specific functions of dramaturgs. Since dramaturgs are frequently treated as an optional extra by Scottish theatre - David Leddy and Dominic Hill, two of Scotland's most dynamic directors tend not to use one - and their role is dictated not by a consistent definition but the needs of a particular production, tying together the process with the job marginalises the visible presence of dramaturgy.
The decision not to use a dramaturg is - ho ho ho - a dramaturgical one. This brings me nicely to the second problem.
Dramaturgy struggles to maintain a popular definition. While it does have many different interpretations, the diversity of its practice ensures that these obscure a clear and concise description. The use of dramaturgy within a sociological context - inspired by Goffman - opened up a dialogue with anthropology and relocated its field from the stage and into everyday life. With its boundaries rendered porous, a tight, theatre-focused definition would exclude its contemporary areas of concern.
As irritating as dictionary definitions can be, they do pull dramaturgy away from its competing functions towards a functional foundation for its use. The emphasis on its wide range of applications, and the roles of individual dramaturges drags into into a vague word that can be used to describe anything that is vaguely a 'performance'.