We do not have a first-class plugin to generate a linear PDF documentation, but are willing to have one. Our plugin lifecycles could enable you to build one, and we might create an official one in the future.
Keep in mind Docusaurus is a good tool to produce interactive docs. A PDF is not very interactive so if you want any interactivity, you'd have to limit yourself to a subset of Docusaurus features.
> Generating only a website for documentation seems like a cultural step back.
No it's actually the trend to have more interactivity. A linear PDF is more like old-school. Don't you like that on the Stripe docs there's a built-in API client?
Supporting PDFs remains useful but it's more an edge case than the main feature of Docusaurus. We have some users willing to edit books using Docusaurus, but most users do want interactivity, and it's definitively a step forward.