I kept thinking that he'd eventually compare it to writing software by hand, and how we're at the end of one golden age. But he never did. So I wonder what the impetus for the essay was.

Ditto. I kept waiting for the AI comparison. My interpretation was less agentic coding than the commodification of LLMs, forcing Anthropic and OpenAI into a pivot to focus on brand. Anthropic's spat with the DoD could be viewed through that lens: losing money on a deal to better position the brand.