my grandma would routinely take her own cooking book, open it, read the recipe carefully and then do something entirely fucking random and say 'if this works i hope i remember to write it down'.
and yet at the same time she was also intransigent with some things. 'this is the best method to peel eggs wow you didn't listen to me time to kill myself', for an example. i think culinary nationalism takes that sort of affectation, which on some level is communicated on a personal level, and tries to make a dogma out of it. it is like taking folk religion and turning it into a scriptural dogma.
I think culinary nationalism is universal to nationalism itself. It's just that Europe's identities are built on the basis of exclusion of neighboring countries, whereas nationalism in, say, Brazil or the United States is built on racial segregation in different forms. What differs from country to country are particularities like these.
With Turkey you have the fact of the post ottoman world being built on balkans scrambling to not identify with Turks, 'the East' and various elements of their traditional cultures while appropriating common pan west asian stuff - which includes cuisine. On top of that you have things like Sweden claiming to have invented 'meatballs with spices from the east actually' because, you know, something popular and so closely aligned with swedish identity can't possibly be 'non european', 'non swedish' or, worse, 'non white'.
With Italy I think what makes them particularly annoying is that Italian cuisine is easy to reproduce. That's kind of the point. Unlike with, say, French cuisine, what adds flair to dishes in Italy are ultra specific regional ingredients. Not culinary methods. To add insult to injury the most influencial italic country in the world is not Italy. It's New York City.
So you take all the contradictions of culinary nationalism and add the fact that italian culture flows not from Rome, but from the United States. Kinda like how the Renaissance came from Asia. The classical italian city states like Venice, Florence, Genoa all did social engineering and reinvented their cultures from the ground up using writings that only Greeks and Arabs had cared about for centuries at that point. But this time the 'source of culture' is the United States, the empire which rules Europe - not the 'Roman Empire' of a wall with a town annex in the dardanelles.