Is word error rate just a vanity metric?

Voice AI vendors love to quote word error rate, usually somewhere around 2 to 3%, as proof their system understands customers. Oliver Shoulson, Agent Design & Engineering Lead at PolyAI, thinks it's one of the most misleading numbers in the business. He and Nikola Mrkšić go through a month of analysis across more than 100,000 real production call turns to explain why. Turns out not all words carry the same weight, most transcription errors are harmless, and task success barely moves...