There is a lot of truth to this, but it's also very much down to domain experts being able to do this to move faster.

Planetscale (assuming they used a agentic development practice) will have pulled this off, to the level of performance that they have, because they have a team of very highly experienced Postgres developers. Their knowlage of Postgres internals will have given them the insights needed to steer the models to a plan that used the architecture as described in the post. That's not something a model can do on its own*

World experts + LLMs = moving mountains.

(* we're obviously seeing something a little different from inside the research teams in the labs. They are showing that the models, when you burn the level of tokens only they can, are able to do novel things from the models own insights.)