It doesn't matter whether diffusion programs or even more rarefied approaches to solution spaces can capture the essence of human-produced art.
Markets are fundamentally about perceived value instead of actual value. Algorithmically generated creative works do not have to compete in the field of actual value; they has to compete in the field of perceived value. Let's be real, almost all customers of art - whether they pay before or after the production - are pretty bad at estimating actual value.
More philosophically, it's not possible to empower humans above human superorganisms. You make a successful walled garden or you fail to reproduce your ideals into the future.