Medium is more or less a blogging platform. I don't think that people who post essays on there have much control over how it displays on any given device/browser, given the minimalist text editor it provides.
I would have imagined the choice of blogging platform is 100% controlled by the author?
I'd love to comment more on the actual blog post subject, but I can't read the article, so I figured giving a headsup would be of interest to the author. Next time I'll just shut up and move on, it's not my loss.
I don't see why it matters who runs medium in this case.