If such a simplistic explanation was true, LLM's would only be able to answer things that had been asked before, and where at least a 'fuzzy' textual question/answer match was available. This is clearly not the case. In practice you can prompt the LLM with such a large number of constraints, so large that the combinatorial explosion ensures no one asked that before. And you will still get a relevant answer combining all of those. Think combinations of features in a software request - including making some module that fits into your existing system (for which you have provided source) along with a list of requested features. Or questions you form based on a number of life experiences and interests that combined are unique to you. You can switch programming language, human language, writing styles, levels as you wish and discuss it in super esoteric languages or morse code. So are we to believe this answers appear just because there happened to be similar questions in the training data where a suitable answer followed? Even if for the sake of argument we accept this explanation by "proximity of question/answer", it is immediately that this would have to rely on extreme levels of abstraction and mixing and matching going on inside the LLM. And that it is then this process that we need to explain how works, whereas the textual proximity you invoke relies on this rather than explaining it.