tl;dr: DHH's AI-generated Rust, Elixir, and Go rewrites of Campfire produce misleading comparisons because the LLM made different implicit trade-offs (backwards compatibility, Redis vs in-process queues, sync vs async locks) across languages, and the benchmarks only measured throughput. Deeper testing reveals the Rust version drops 99% of notifications under load due to a small broadcast channel capacity, while Elixir's unbounded mailboxes trade memory and latency for delivery—neither is strictly better. The takeaway: language choice doesn't automatically solve concurrency problems, and you still need to understand code, failure modes, and trade-offs.