Simplicity of use, and distribution. In certain ways, Medium's social component makes it much easier for other people to find and read it vs. a personal blog (unless you already have a following.)

Github is a closed platform too

you don't need github pages to deploy jekyll. While source code of github pages itself is not available, since it supports a open standard, which can deployed to a webserver/CDN directly without major changes, I would consider it to be open.

Just to follow this to its logical conclusion, the webserver may be running Apache or Nginx on Linux, but there are likely to be proprietary blobs in the drivers and the firmware is probably closed. Plus, much of the hosting company's networking hardware is probably running proprietary software.

IANANE (I Am Not A Network Engineer) but I imagine with open firmware like Coreboot and networking distros like Cumulus and pfSense (BSD) and the whole Open Compute Project it might be possible to run a completely open-source hosting company. Well, no. Your UPS's and other auxiliary hardware are probably running closed OSes. Darn.

Cumulus contains a large portion of closed-source code, including all the driver code provided by Broadcom, which is where much of the interesting stuff happens. (I assume their Mellanox products are the same, though I'm not familiar with them)

I'm not aware of any efforts to write open source drivers for any high speed ethernet chips, though I haven't looked much. Intel's (formerly Fulcrum) switch chips have open data sheets (but not the reference code, simulators, etc) so it would at least be plausible to start there.

someone is (or was?) trying: https://www.vikings.net/

Perfect is the enemy of the good.

Exactly. But that is not to say, that it is hassle free. I am using jekyll on my private page (till I eventually get the rewrite done). It is nice, to be able to write in .md and to then have two aliases in my bash_profile to produce a preview version on a subdomain and finally to deploy to live environment. But really it was a pain in the butt to get there. Also having images in my content makes things even harder.

There were so many roadblocks, that I took on having a ton of fun - but nowadays I would love to just have an easy way to write text, without thinking on design, formatting, code embedding and so on...

Sometimes I am scarred by myself when I find myself wishing I still had WP installed. shiver

[Edit:]

Also this way he might have some additional exposure of his novel by people stumbling upon him while on medium.

It's using open standards. It's an open platform. Unless you consider every webhost to be a closed platform?

I can recommend Ghost it's a light blogging cms

I've recently switched to Ghost after using Medium and Wordpress for other things. Ghost is by far my favorite, it's really nice.

I have a github pages blog, but I seem to find it psychologically easier to write directly into a browser window.