His main point, though, is this:
I have a colleague ... who spent two months earlier this year building a system that should have been designed by someone with formal training in data architecture. He used the tools well, by the standards by which use of the tools is currently measured. He produced a great deal of code, a great deal of documentation, a great deal of what looked, to anyone who did not know what to look for, like progress. He could not, when asked, explain how any of it actually worked. The work was wrong from the first day. The schemas, and more importantly the objectives, were wrong in a way that would have been obvious to anyone with two years in the field.
I've been reading many rants like that lately. If they came with examples, they would be more helpful. The author does not elaborate on "the schemas, and more importantly the objectives, were wrong". The LLM's schema vs. a "good" schema should have been in the next paragraph. That would change the article from a rant to a bug report. We don't know what went wrong here.
It's not clear whether the trouble is that the schema can't represent the business problem, or that the database performance is terrible because the schema is inefficient. If you have the schema and the objectives, that's close to a specification. Given a specification, LLMs can potentially do a decent job. If the LLM generates the spec itself, then it needs a lot of context which it probably doesn't have.
This isn't necessarily an LLM problem. Large teams producing in-house business process systems tend to fall into the same hole. This is almost the classic way large in-house systems fail.