Sure, serving static files will always be the fastest, but this is for people looking for a service like Medium, or Blogger, where there's no need to handle anything locally.
to be clear, you don't _need_ to do anything locally. It's possible to use static blogs without touching your site and there are lots of competing tools out there that will give you a web front end to your static blog.
For example. I use Hugo, with Forestry.io and don't have to touch my filesystem (or even my personal computer) to blog. I just go to a web page like all the CMS blogs.
I'm self-hosting rather than using something like netifly so the setup was a bit more geeky BUT it's totally doable and doesn't have to be tooo geeky.
