Static site generator is a very well defined thing. Content, static pages out.

This isn't 'generating static pages'. It's rendering a page every time you access it, you've just moved the rendering to the browser's JS runtime.

I don't get what the fear around building is. Many static site generators don't even require you to install additional toolchains[0], so churning out static HTML content from markdown should be just as easy.

It's better to spend just a couple minutes setting up a static site generator into your workflow than to have every user who pulls up your STATIC website perform template rendering and all that garbage. I know computers are fast and it doesn't seem like it really makes that much of a difference, but thinking like this often leads to inefficiencies in other applications as well.

[0]: https://github.com/keats/gutenberg

I mean it's hard to compete with installation instructions as simple as "commit this file in the root of your docs/ directory" and point GH pages at it.