The "common vocabulary to discuss design decisions" benefit is underrated. I've been building automation agents and the biggest unlock wasn't technical—it was having clear mental models for routing decisions. Client-server is the simplest pattern but it scales: my agent routes tasks to different models (Haiku/Sonnet/Opus) based on complexity, just like client-server routes requests to appropriate backends. Architecture patterns aren't just for distributed systems, they apply to AI orchestration too. The routing layer is the architecture.