Jono Alderson spent years as Head of SEO at Yoast, where he shaped how millions of WordPress sites handle structured data and technical optimization. Before that, he worked agency-side and built his reputation on the unglamorous work of making websites actually function for search engines. He now operates independently, consulting on technical SEO while developing frameworks for understanding how AI systems process and evaluate web content.
His concepts have given marketers a vocabulary for changes that were previously difficult to articulate. The "zombie web" describes sites that are technically online but invisible to AI because they never offered unique value, just repackaged commodity information that LLMs have already memorized. The "machine immune system" captures how AI models automatically filter out marketing fluff, treating superlatives and promotional language as noise rather than signal. These aren't academic labels. They're diagnostic tools for understanding why content that performed well in traditional search gets ignored by AI systems.
On the podcast, Jono argued that 90% of websites are now functionally dead. AI agents have already extracted everything useful from commodity blog posts and generic content. The gap between what brands claim on their websites and what Reddit reviews reveal has become a measurable credibility penalty in AI-generated responses. His prescription is uncomfortable for marketing teams: stop optimizing your website and start fixing your return policy, your customer service, your actual product. The engineers handling logistics and fulfillment are now doing more for search visibility than SEO teams. That's the reality of what he calls upstream engineering, the idea that the most impactful SEO work happens outside the SEO department entirely.
90% of websites are now zombies. AI agents have extracted all their value, and marketing fluff triggers their immune system.
