Children are not railroad trains. They don't learn at an even rate. It strengthens their ability to comprehend written messages and to communicate them verbally. It exercises the students' imaginations and thinking skills. It develops their taste for good writing.
Students are better able to discern between good and bad literature.
It advertises reading as a pleasurable and desirable activity. E.G. The Caxtons , 1849. How Children Learn . Dell Publishing, 1983. The Home School Manual .