Agent parallelism is cheap in the same way tapwater is cheap — that is, you pay exactly for what you use at a given moment, no more and no less.

Humans are a lot more expensive, it takes ~a year to find, interview, hire, onboard and offboard an employee, while an agent can be spun up for 10 seconds, do its work and vanish back into the ether.

Agents are lambda functions where humans are bare-metal servers that you have to rack yourself.