Claim: Platform feudalism constitutes a structural threat to democratic self-governance that cannot be addressed through content moderation or platform regulation alone. Argument Style: Deductive. Each step builds on the previous. To dispute the conclusion, a flaw must be found in one of the supporting claims. Argument: 1. Democracy requires a public sphere in which citizens can form, exchange, and revise political opinions based on shared facts and open deliberation. 2. A public sphere has structural properties — it determines what topics are visible, which voices are amplified, and what counts as credible evidence. 3. The dominant public sphere today is hosted on privately-owned platform infrastructure (Meta, X, TikTok, YouTube) whose structural properties are determined by profit-maximizing algorithms, not democratic principles. 4. Profit-maximizing algorithms systematically amplify outrage, tribal signaling, and emotional activation because these generate more engagement than considered deliberation. (This is documented in internal platform research and peer-reviewed studies.) 5. Therefore, the structural properties of the current public sphere systematically work against the conditions democracy requires — not incidentally but by design. 6. Content moderation addresses symptoms (specific harmful content) but not the structural cause (the algorithmic incentive to maximize engagement over democratic quality). 7. Platform regulation that preserves the underlying profit-maximizing structure similarly addresses symptoms. 8. Varoufakis: platforms are not companies operating within markets — they are lords controlling the territory. Rent extraction from users (attention, data, political influence) is the business model; the public sphere is the territory being rented. 9. A democracy that hosts its public sphere on private infrastructure it does not control has delegated a core sovereignty function to actors whose interests are structurally opposed to democratic quality. 10. Therefore: platform feudalism constitutes a structural — not merely incidental — threat to democratic self-governance, requiring structural responses (public infrastructure, open standards, democratic ownership) rather than behavioral regulation.