PCBs are basically designed using graphic editors. The editors all have their own standards and don't really import pure text pass the netlist. Simply importing from one to the other is quite painful.

It's basically trying to build a really really complicated SVG and llms struggle with simple svgs. And that's only the Gerber, there's also the whole schematic that needs to be done first from which the Gerber is built from.

PCB design tools are basically made to make our lives easier and avoid mistakes, but it makes it incredibly difficult for any kind of LLM, even before we hit all the intricacies involved in it.