In my opinion, subagents (or more generally, "agents as tools" as a pattern) are an order-of-magnitude level feature. Soon every CLI agent will have them as a first-class feature (you can get them via custom scripting right now with and CLI agent, albeit less ergonomically).

The ability to isolate context-noisy subtasks (like agentically searching through a large codebase by grepping through dozens of irrelevant files to find the one you actually need) unlocks much longer-running loops, and therefore much more complex tasks.

And you don't need a system this complicated to take advantage of it. Literally just a simple "codebase-searcher" agent (and Claude can vibe the agent definition for you) is enough to see the benefit first-hand. Once you see it, if you're like me, you will see opportunities for subagents everywhere.