Unless we're talking about figma-like web apps, Content is usually a different department than development.

I know it's becoming more and more outdated nowadays, but if a magazine or a news website is still written by humans rather than AI they need a way to provide formatted text and media, and preview the output.

On the other hand I should add that i've also seen an upward growth in CMSes like WordPress being used exclusively as Online Editors, with content ultimately being exported trough REST to completely different backends and frontends, like a Firebase/NextJS infra.