To generalise or specialise?

Interesting study that leads to a mundane/obvious conclusion. In the final paragraph it says:

   These results go against some long held beliefs [...]
   that societies require specialisation to be productive
   and efficient. However, D'Orazio thinks that, at least 
   for biological purposes, the new model will set a
   standard for future work.

In the cookie shop example -- wouldn't you say that an employee who can both make and sell cookies is still very specialized? Two specializations perhaps, but specialized nonetheless. Even if you don't take the second order benefits (that having several specializations leads to better insight/productivity in both tasks) into account any model that claims that specializing in one single thing is the optimal division of labor is clearly wrong.

In math-speak: the commonly held belief is that for any society without division of labor you can get to a better/more productive society by introducing some version of division of labor. The belief was never that for any society you can get a more productive society by increasing the division of labor. (Obviously false because specialization itself bears a cost [education, etc] and the marginal benefit of additional specialization decreases the more specialized somebody is, therefore there must be a point where additional specialization is actually harmful instead of beneficial. This contradicts the claim that specialization is unconditionally good.)

Mathematical model: nice.

New or counter intuitive results: not as far as I can tell.