@pimoore @warner I think the bit at the end (presumably a hex number) is a unique identifier that makes it possible to get to a particular post by way of several different addresses. For example, I believe that all of these will lead to the same page:
(There’s also a fourth possible address which has an “@“ in it.) Obviously, people post a lot of stuff on Medium, so an identifier for each post, independent of the username, is going to look a bit forbidding. It doesn’t seem to have anything directly to do with lock-in.