There was an article on the Guardian about the quality of Italian coaches last friday I guess, talking about Coverciano, but the main reason probably is because they have decades of being at the highest level and they love tactics, for instance, the coaches I admire more related with italian football, one of them is Zdenek Zeman who returned yesterday at Pescara last placed and they won 5:0.
He is Czech but all his carrer is related with Italy, also like Sacchi and Sarri, this for ones who look more to quality of football, because if you want to look to those who won a lot you have Trappattoni, Cappello, Lippi, Ancellotti.
And it is not only Italy, Germany has lot of progressive coaches, Argentina has all types of coaches, Spain and Portugal do have some nice coaches too.