I don't like WordPress, but Jamstack will never overtake WordPress adoption quite simply because Jamstack is too complicated.

In particular, it will never find an audience among non-technical users which is a very different audience from technical users who often think only of their own likes and needs.

If you don't like WordPress, there are more modern CMS apps with modern coding practices (often written in PHP). They aren't part of the Jamstack and but are often much simpler to deploy.