People write and publish without such incentives, without the goal of turning up on page 1 of Google search results, and don’t care about being “beaten” by whatever alternative publication. And at least so far, truly good and useful content generally does find its audience, even without SSO.

There’s also a lot of content that can’t be meaningfully replaced by LLMs, such as people writing about their side projects (such as the current top HN submission https://news.ycombinator.com/item?id=41154135), product reviews, or more generally, reports of personal experiences, or personal takes on whatever topic.