The analogy falls apart when Wal-Mart is the only store in existence. Then you can't just "make a new store" because it's impossible to compete. That's the point that we are at now. The major platforms are succeeding at stifling voices that they dislike and there are few or no alternatives. Saidit is still growing and has a high chance of dying out once the people banned from Reddit realize they don't need any social media.