My go to example is a simple payment order form (or sometimes forms in general depending on the CMS/static site generator).
If I use this tool, there are no forms. Client comes back a year from now and says they want to add a form. So after much fuss we move to something with forms. Then another year later, they want to take payments for $20 T shirts. We could spin up a 3rd party service but sometimes that makes things even more complicated.
If I started on WP, I can use one of the dozen form builders that support basic payments and I would have saved my client thousands of dollars of transfer fees and hours of my own time converting data between these platforms for little gain.
I say all this as someone who builds mostly WordPress sites at this time, though I’m always trying out new things too.
If that's true, it seems like the kinda missing bridge/glue between generators like Jekyll/Hugo; allowing static content without needing to be a web dev.
But seriously, in my experience, I'd rather use something other than Wordpress. There are lots of things it does well, but not usually for the projects I work on. Use the tool that works well for the project.