In Ray Bradbury's classic novel Fahrenheit 451, firemen don't put out fires; they create fires to burn books.
The totalitarians claim noble goals for book burning. They want to spare citizens unhappiness caused by having to sort through conflicting theories.
Censorship Is Control
The real aim of censorship, in Bradbury's dystopia, is to control the population. Captain Beatty explains to the protagonist fireman Montag, "You can't build a house without nails and wood. If you don't want a house built, hide the nails and wood." The "house" Beatty is referring to is opinions in conflict with the "official" one.
If you don't want a man unhappy politically, don't give him two sides to a question to worry him; give him one. Better yet, give him none. Let him forget there is such a thing as war. If the government is inefficient, top-heavy, and tax-mad, better it be all those than that people worry over it.