It doesn't solve the same problem as a static site builder. e.g. A static site builder lets you build templates using whatever plain html/css you want, and then you can write individual pages in markdown and have them generated using your template.
I think this is the way to go if you're not one to change the HTML very frequently. It can be a repetitive process to update HTML for each page if you've wound up with lots of them. If that's not so much a concern, go for it!
It’s fine until you have a list of blog posts etc that you want to generate your static site from
How is that different than just copy pasting a new page?
What if you want to update the template? You'd need to change it on every page. That's fine if it's only a dozen, but does not scale well.
I used to have a 5 page portfolio site and it was a pain even with that few copy/pastes to do in order to update my header. Static site generators ftw.
If you want the pages to share a header, footer, and menu, it can be a pain because if you ever want to change something in a shared component, you'd have to do it for every single page.
+1. I don’t get it either. Maybe the ability to use Markdown?