A brain that only performed text output might be modeled like that, which is exactly what these represent.

But no brain we've ever seen was subject to that constraint, so it's a sort of fantastical target for modeling and doesn't say reveal anything about brains themselves or the various entities that seem to bear them.

Modeling one feature of a grossly simplified and incomplete brain is a creative approach to computational research and proved very fruitful, but there's no reason to leap from that success to the idea that real brains do work that way or even that the imagined only-textual-parts must.