Politicians: a backdoor that can be used by the police for investigating crimes, but not by criminals themselves.
HN users: no backdoor at all, especially not a backdoor that can be used by the police.
Politicians: technology that strengthens the power of the state, against crime, but also militarily, for spying on enemies both foreign and domestic.
Citizens: defensive architecture that prevents the state from preventing free speech.
This is especially relevant in the era of AI, where the cost of mass surveillance is virtually zero, and is incredibly powerful at sentiment analysis and summarization. Free speech is threatened when any statement can and will be used against you.