I haven't used these things for writing recreationally for a while (since the Claude 3.X days), so my opinions might be outdated - but they definitely weren't bad - after all they had a huge library of witticisms to pull from, and like Stable Diffusion that pulls from master artists, so do LLMs from skilled writers. Pro writers did come up with an absolute dearth of interesting ideas, and there are mountains of skillfully written prose out there - and its all in the training data, and AI is quite good at pulling from it.

The advantage of the writing vs images, is that it takes longer to absorb the whole with text, so its less apparent that the whole thing doesn't quite come together.

My problems was with Claude's prose and ideas is that it kept recycling the tropes and phrases after a while - something that has been observed that these models have very strong statistical biases - when asking for a random number for example, LLMs are far more predictable than even humans, this shows up in unguided writing exercises.

But as for actually crafting text that is both terse and to the point - such as oneliner explanations, or writing summaries - these models are quite bad. The best I have seen is they could turn a given length of prose into an even longer version - with generally some loss in the tonal accuracy or the points made in there.

As such they are a terrible tool for professional communication, but unfortunately, lots of people have started using them for exactly that.