I think it's just the nature of being inside an academic discipline rather than outside it. If you look at evolution, for instance, there is a proper way for it to be discussed in high school classes, but in universities there is a lot of dialogue about the actual processes of how it actually works and what has has not been explained.
Any area where people are getting Ph.D. degrees will have points of serious debate, but the people who emerge with the Ph.D.s [gosh that looks ugly] set about as standard bearers to the rest of the population who really don't want to know why the rules are the way they are.
They don't grant Ph.D.s in handwriting, I don't think, though I'm sure there are Ph.D.s in education or criminal investigation who wrote dissertations on the subject of handwriting. Maybe.
There is also that joke about wherever you have two [insert talkative ethic group members] you will have three opinions: the opinion voiced by the first person, the opinion in opposition to the first, and the opinion actually held by the second person.
