Question

why did the roman catholic church impose control over publisher and booksellers

Answer 1

Because it had tensions that it would break bond

Answer 2

In the 16th century, a miller named Menocchio reinterpreted the message conveyed through the Bible and gave a new opinion about God. These viewpoints enraged the Roman Catholic Church and they were trying to repress these ideas. They finally executed him.

However, the word had spread and they thought that the other books which led Menocchio to have adverse ideas about Catholicism. So, they started to restrict many publishings and controlled the booksellers from selling books that questioned the faith. So, from 1558, the Roman Catholic Church started to have an index of all the prohibited books.