Answer:
Because the role of Catholic church was the strongest in those regions, especially in Italy and Spain.
Step-by-step explanation:
Namely, while Protestantism started spreading from Germany, it had little or no influence in Spain and Italy. The introduction of Inquisition in Spain disabled people to oppose the Church. Not only that Protestantism wasn't spreading there, but many people were obliged to convert themselves to Christianity.
In the same time, Catholic church had its center in Europe, and it was impossible to fight against it there.