Even in a digital-media landscape that is dotted with odd startups, Medium is a strange beast: founder and former Twitter CEO Evan Williams has said it uses the magazine as a guiding metaphor, and yet it is also a platform for anyone to publish. It has “collections,” which are sort of like mini-magazines, and yet the site itself is like a magazine. As part of the relaunch of Matter, a journalism startup that Medium purchased last year, Williams tried to put some of the questions about his site to rest, but instead seems to have only compounded the confusion.