The reason writing is hard might be that post-training pulls style into a particular direction. In other words, big labs are much more interested in making "AG

The reason writing is hard might be that post-training pulls style into a particular direction. In other words, big labs are much more interested in making "AGI" than in making a good writer, especially as what qualifies as "good writing" is rather subjective. E.g. before AI use of metaphors and rhetorical devices were generally a sign of a good writing. Of course, not if you keep spamming the same rhetorical device - but a stateless AI can't know which one it is over-using.