tl;dr: Writers who make Substack their primary home are digital sharecroppers—vulnerable to policy changes, algorithm shifts, and corporate decisions, just as previous generations learned with Medium, Tumblr, and Twitter. The author advocates for the POSSE model (Publish on Own Site, Syndicate Elsewhere): own a domain, treat your website as the source of truth, and use platforms like Substack purely as distribution channels. John Scalzi's 28-year run on whatever.scalzi.com is cited as the ideal approach.