The many problems of the "marketplace of ideas" metaphor aren't specific to the notion of an exchange of ideas, but of any marketplace. It's simple, direct, immediate, minimum-viable-standard ideas, goods, services, products, etc., which dominate in any market. It doesn't matter if these are ideas, hamburgers, blockbuster movies (arguably ideas), electronic devices, or hamburgers. The marketplace puts a general premium on simplicity, mass appeal, and immediate benefit (even if this carries long-term harm).
The failures aren't specific to ideas. This is simply what marketplaces, and market-based economic systems, do. It's a failure of any such system.
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