Great points. Words allow one to communicate an approximation of part of what one knows.

Agree about expertise being inseparable from the 'world model'. When someone tells us something, they're assuming that we know a certain amount of background knowledge but, in reality, we never have exactly the missing pieces that the speaker is assuming we have because our world model is different. It can lead to distortions and misunderstandings.

Even if someone repeats back to us variants of what we've told them at a later time, it doesn't mean that they've internalized the exact same knowledge. The interpretation can be different in subtle and surprising ways. You only figure out discrepancies once you have a thorough debate. But unfortunately, a lot of our society is built around avoiding confrontation, there is a lot of self-censorship, so actually people tend to maintain very different world models even though the surface-level ideas which they communicate appear to be similar.

Individuals in modern society have almost complete consensus over certain ideas which we communicate and highly divergent views concerning just about everything else which we don't talk about... And as our views diverge more, it narrows down the set of topics which can be discussed openly.