Well, what do you expect? LLMs are trained on blithering, mostly from web sites. So you get blithering out.

There's an important point in the article, that forcing a style onto an LLM is lossy. Although he doesn't seem to mention it, forcing a style may result in the insertion of new blithering, possibly made up as a hallucination.

I think that was a good enough explanation for gpt3.5 -- these days, labs are extremely capable of post-training phases that eclipse that kind of training phase -- and hence of choosing whatever style or tone they wish.

eg., OpenAI has gone a long way to making reasoning token-efficient by having reasoning piovot off terse langauge -- whereas anthropic appears to be doing the opposite.

is it lossy though? That didn't make sense to me. You can tell it to use Simplified Technical Language and also still have it give you all the detail. it's just another piece of the prompt that produces the output. it's not like there's "pure" llm output and then "lossy" output guided by a prompt.