Repeatedly, in the context of discussions and questions, including questions asked here, I keep running into the topic of Aspect Permissions. To further clarify, I'm talking not about Extras, nor about establishing extrinsic setting facts, but rather about them changing intrinsic properties and abilities of characters - narrative permissions for the characters - without engagement with the FP economy. The cleanest examples would be when one PC can do something (with or without a roll), while another can't even try, due to the Aspect differences between the two.

People always seem to have a lot to say on the topic (often in a free-form-thought-of-the-day manner, similar to the style of Book of Hans), with confident 'this is how the system works' which seem very much not obvious to me, like they're building upon some part of the fundamental system texts that I'm missing.

And I'd like to find those parts of the text that I seem to be overlooking. That is, to find the basis, the common root for the conclusions that seem to be rather common (and similar-sounding) among the veterans of the system's fandom, read it more attentively.

The closest thing to a basis that I found seems to be the 76th page of the core-book, where it talks about using Aspects for roleplaying (with the given example showing how a GM roleplays NPC reactions to the PC's Aspect). But there seems to be a huge leap from 'NPCs know you are the Strongest Man in the World and their behaviour is informed by that knowledge' to 'You are the Legendary Tomb Raider, so of course you can understand and speak the obscure isolated dialect of Nahuatl that you just encountered for the first time'. What am I missing?