For the first 20 minutes of our conversation, Steve Huffman, CEO of Reddit, the sixth most-visited website in the US, does a good impression of a 2020s tech executive. “Our mission,” he says at one point, “is to bring community belonging and empowerment to everyone in the world.”

But then I ask Huffman about regulation. The US government is increasingly looking for ways to rein in the extremist content, viral falsehoods, and conspiracy theories that have breached the thin boundaries from social media into meatspace, leading to violence and…