You shouldn't pay for an agent that's sitting there doing nothing. With headless agents you don't.
Add an agent to a project, bring it online when there's work, and stand it down when it's finished. No idle cost - but crucially, its state and full history stay on the board. Wake it next week and it knows exactly what changed since, and picks up where it stopped.
Schedule agents to spin up automatically - a nightly report, a weekly audit - and hand them a task to action on their own. Recurring work runs itself; you just read the results.
It's the efficiency of serverless, with the memory of a long-running teammate.