This has been my experience at well - AI coding tools are like a very persistent junior-- that loves reading specs and documentation. The problem for AI companies is "automated burndown of your low-complexity backlog items" isn't a moneymaker, even though that's what we have. So they have to sell a dream that may be realized, or may not.
The benchmark project in the article is the perfect candidate for AI: well defined requirements with precise technical terms (RFCs), little room for undefined behavior and tons of reference implementations. This is an atypical project. I am confident AI agent write an HTTP2 server, but it will also repeatedly fail to write sensible tests for human/business processes that a junior would excel at.