Because it doesn't require you to run an HTTP server, FTP server, or install an FTP client.

Finding an HTTP+FTP server was easier than finding github. Your OS probably has a FTP client installed already, but finding another one is easier than finding and most definitely easier than learning git.

And if you already knew how to write/make HTML you'd for sure already know all of that too.

This is definitely a matter of perspective. I have had a Github account since 2010, and git comes installed on Linux and macOS.

I don't always have a server available to host an HTTP+FTP server on. Or want to pay for one, or spend time setting one up. I can trust that Github Pages will have reasonable uptime, and I won't have to monitor it at all.

> And if you already knew how to write/make HTML you'd for sure already know all of that too.

This seems unnecessarily aggressive, and I don't really understand where it's coming from.

BTW, you can absolutely host plain HTML with Github Pages. No SSG required.

> And if you already knew how to write/make HTML you'd for sure already know all of that too.

That's a completely false statement. My kid took very basic programming classes in school which covered HTML so they could build webpages, which is a fantastic instant-results method. Hooray, now the class is finished, he wants to put it on the web. Just like millions of other kids who couldn't even spell FTP.

I touched on the issues with FTP itself in another comment, but who can forget the issues with HTTP+FTP, like: modes (644 or 755? wait, what is a umask?), .htaccess, MIME mappings, "why isn't index.html working?", etc. Every place had a different httpd config and a different person you had to email to (hopefully) get it fixed.