That's true. I.e. it's not that they're not capable of doing better, it's just whoever's prompting them is typically too lazy to add an extra sentence or three (or a link) to steer it to a different region of the latent space. There's easily a couple dozen dimensions almost always left at their default values; it doesn't take much to alter them and nudge the model to sample from a more interesting subspace style-wise.

(Still, it makes sense to do it as a post-processing style transfer space, as verbosity is a feature while the model is still processing the "main" request - each token produced is a unit of computation; the more terse the answer, the dumber it gets (these days it's somewhat mitigated by "thinking" and agentic loops)).