This is a huge difference. Writing is a two-step process: idea generation, and selection. The first part is similar to what a randomized algorithm or an LLM might do, in smaller chunks (and indeed, the history of aleatoric processes in creative endeavors is long -- see Oulipo for one example in literature.)
The second step -- selection -- is the heart of creativity. It's about taste. Knowing what is and isn't "good."
When you consider the creative processes of Dada, Duchamp, Brian Eno -- I think it becomes clear that this automation of creative generation is a continuation of existing trends rather than a sudden disruption.
If an LLM were able to, on its own, generate and select poems, independently developing a new style of poetry that resonated with readers -- that would be something else entirely.