https://electricliterature.com/
https://medium.com/the-economist
https://medium.com/@generalelectric
You'll notice the engagement is absolutely terrible. Between 10-100 likes, and even those stats are inflated by (no doubt terrified) Medium employees. Keep in mind, the rough "like" to "view" ratio is ~1:100, so hardly any of these posts are even cracking 10,000 views. Those are okay numbers when you're paying your writer/marketing guy $200 per post. Hardly the foundation for a company valued last year at $400M.
Of course, Medium could monetize with banner ads like every other site, and it does have enough traffic to do that (it's the 371th most visited site in the world.) However, most writers only write on Medium because there aren't any ads. If Medium suddenly started monetizing on my content "YouTube style" I would leave them for Wordpress in a second. The Medium community is fine (they'll drive 100-1000 views per post on my pieces) but that's not enough to justify graffitying my content with ads.
It seems like there's a major identity crisis going on here. On one hand, a lot of great pieces are published on Medium. (Perhaps not as many since Medium de-funded/spun-out their flagship in-house publications, Matter and Backchannel). But there's also a crazy amount of crap. The top stories on Medium are almost invariably listicles and trite "How I Xed my Y in Z days".
I get the feeling Medium set out to position itself as a curated Wordpress (which might justify that gargantuan valuation) but these days it feels pretty much like an awkward, less popular, and slightly more erudite Buzzfeed.*
*Buzzfeed is not without its own problems. See traffic stats here: http://www.alexa.com/siteinfo/buzzfeed.com