Think about it.
What's the most expressive medium we have which is also absolutely inundated with data?
To broadly be able to predict human speech you need to broadly be able to predict the human mind. To broadly predict a human mind requires you build a model of it, and to have a model of a human mind? Welcome to general intelligence.
We won't realize we've created an AGI until someone makes a text model, starts throwing random problems at it, and discovers that it's able to solve them.
Language is way, way far removed from intelligence. This is well-known in cognitive psychology. You'll find plenty of examples of stroke victims who are still intelligent but have lost the ability to produce coherent sentences, and (though much rarer) examples of people who can produce clear, eloquent prose, yet are so learning and mentally challenged that they can't even tell the difference between fantasy and reality.
This is a non sequitur. The human mind does a whole lot more than string words together. Being able to predict which word would logically follow another does not require the ability to predict anything other than just that.
> Being able to predict which word would logically follow another does not require the ability to predict anything other than just that.
Why? Wouldn't you expect that technique to generally fail if it isn't intelligent enough to know what's happening in the sentence?
The expressiveness of language lets this be true of almost everything.