> is your argument now that an LLM can capture arbitrary state of the wider world as a general rule, eg pretending to be a Swift compiler (or LSP), without overfitting to that one task, making all other usages impossible?

Overfitting happens, even in humans. Have you ever met a scientist?

My points have been only that 1: language encodes a symbolic model of the world, and 2: training on enough of it results in a representation of that model within the LLM.

Exhaustiveness and accuracy of that internal world model exist on a spectrum with many variables like model size, training corpus and regimen, etc. As is also the case with humans.