2016 saw the company make a big push to become the publishing platform for brand-name media businesses. Bill Simmons' The Ringer, The Awl, The Bold Italic and Think Progress all signed up to use Medium as their backbones. In order to support these names, Medium began building an ad platform to pull in enough cash to keep the lights on. Williams explained that "the strategy worked in terms of driving growth," but couldn't solve the issue of "driving payment for quality content."
Williams is also disdainful of the current ad-supported model that drives so much of the web publishing we see today. He wrote that the existing system is paid for by "corporations who are funding it in order to advance their goals." He added that people are "dissatisfied with what they get from traditional news and their social feeds." You can interpret his words as an indirect indictment of Facebook, which has profited from fraudulent news created to drive click revenue with little regard for truthfulness.
As a consequence, Williams is pushing Medium to devote what time and resources it has left to finding a way to get people to pay for "good" content. So it's shutting its New York and Washington DC offices, shedding executives and generally going into siege mode. But, as so many other industries whose ability to make money was harmed by the internet have learned, it's hard to wean people back off free stuff when they're hooked.