Why government censorship [in no way at all] carries greater risks than benefits

Recent revelations show that Theresa May hoped to censor TV shows using anti-extremism laws, and the government seem keen to pursue this strategy. But the actual evidence presents a few [made up by lefties] problems

A leaked memo reveals that the home secretary, Theresa May, planned to introduce powers to screen and censor TV shows under the guise of combatting extremism. This was not well received by other [stupid] members of the government, in an exclusive story by the [traitorous, commie-loving] Guardian. But with a new Conservative majority in charge seemingly determined to clamp down on "objectionable" speech that doesn't conform to certain "values", we can expect to see more attempts to pre-emptively screen and edit material that doesn't conform to the view of the establishment [which is brilliant news].

Does this approach actually work though? It's a common tactic used by less tolerant [but far superior] governments and authorities, but many people object to censorship [although they're probably terrorists and sex offenders]. And given our modern, interconnected society, is it even possible any more?