Easier said than done, and anyone seriously planning to do this ought to consult legal counsel to come up with the most creator-friendly terms that also serve as CYA (against new legislation that attempts to remove "safe harbor" from copyright violation claims, and against authors who don't understand what copyright IS). I wouldn't exactly demonize Medium for this, but I do plan to leave. There are just too many ways this could be abused by a company that sees itself as a "publisher.")