[all2]

High SERP ratings come from multiple things:

1. If you use Google signed in, they know (I assume) you preference technical material (which is the bucket Medium falls in)

2. On-site links; one of the most powerful (and underutilized methods of SEO) is interlinking pages on a site. I'm not sure why this is the case, but it can be a determining factor in top-ranked sites (see Wikipedia as the canonical example of onsite linking).

3. Inbound links; lots of people link to Medium content. If Medium uses Google's tracking tools, Google has a good idea of the inbound traffic and can adjust based on the site's popularity.

None of this has to do with user experience. Unfortunately.

I'm sure there is more (like page load times, how information is organized in the HTML, etc.) that factors in, but these are the ones that occurred to me.

[jetrink]

Page load time should include the time it takes to clear away the nag screen before you can see the content. That is easily 2000ms for most people.