1. Printing machines were not allowed among many Muslims because of the misunderstanding of some Shaikhs about the procedure  of printing machines. Sunni Shaikhul Islam in Istanbul (Capital of the Sunni Othmani  Empire ) and Sunni leading Shaikhs did not allow using printing machines in printing religious books for around three centuries after the printing machines were used in Europe in the 15th century. It was in 18th century or 19th century when Sunni Shaikhs allowed using printing machines. That delay of three centuries caused lot of harm to the education and learning chances for millions of Muslims. Shia scholars allowed using printing machines and many books of Shia Hadeeth were printed in Iran and India where Shia scholars were active like Lucknow, Kalkutta, Bombay and Hyderabad.

More important than printing is compiling the books of Hadeeths. Sunni rulers of Saqeefah were openly against writing, narrating, learning and teaching the Hadeeths. Abu Bakr asked his daughter as she said, to bring to him all the written Hadeeths and they collected five hundred Hadeeths. He spent a restless nigh till next morning when set all collected 500 Hadeeths in fire. (Tathkirat al-Huffadh by al-Dhahabi , V. 1, P. 5).

Omar ibn al-Khattab was very strict against narrating and Hadeeth from the Prophet Muhammad. He gave strict orders to people not to narrate, mention, teach,bleary or write any Hadeeth. He put leading Sahaba like Abdullah ibn Mas'ood,  Abu Thar and Abu al-Dardaa' in jail because of their narrating Hadeeths. ( Al-Mustadrak 'ALAL Saheehain by al-Haakim al-Nisabori, 1:193.

The famous Sunni Shaikh, Abu Bakr ibn al-'Arabi mentioned his book Al-'Awaassim min al-Qawaassim 1: 87 that Omar put Abdulllah ibn Mas'ood and number of Sahabah in jail for one year in Madinah till he was killed because of their narrating Hadeeths which they heard from the Prophet (SAWA).

Wassalam.