Its there because it works.
But Sunni-fascists deploy blasphemy laws not only against other religions but also against Shias.
Kuwait is now formally joining the club with this law ..the real target of which appear to be Shiites…they are the ones accused of blaspheming against the wives (read Hazrat Ayesha) and companions (read Abubakr, Omar, etc) of the holy prophet. This strategy has already put the shias in Pakistan on the backfoot. It has also made many of them “practically liberal”…just like fear of persecution makes many Muslims in India very dedicated secularists…but its a very confusing situation for many Shias. Their own tradition emphasizes love of the prophet and prosecution of blasphemers even more than the Wahabi-ized Sunnis, so being targeted by blasphemy laws that they would love to apply to others has created very painful cognitive dissonance for some of them.
Its going to be a very confused and violent learning process.