Once you want to add more people to any business, you need to add even more people to that business.
Lets say you have 10 engineers and want to add another. Suddenly HR's workload has tipped over the limit and you need more HR people. Now communication is fracturing for those 10 engineers and you need a Product Manager and an Engineering Manager to centralise the steering and cohesion of those 11 engineers. Now budgets, payroll and accounting has increased and you need another Finance person.
Suddenly your office is too small so you need a bigger office and an office manager.
This is obviously a contrived example, but having worked at very early stage startup, a mid sized startup and a global megacorp while seeing all of them go through various growth cycles you start to appreciate how headcount can creep in ways which feel indirect to the most pressing problem at hand (ship more features, deliver more customer value).
You see it software terms too - as your software project scales suddenly you need more infra, your CI environment gets more complex. Suddenly your workflows don't scale as too many engineers are working on the same code, so you rearchitect (components/microservices) then you need to start building dev tooling and metrics/observability....
I guess as some kind of system scales, the leverage you gain from adding a thing to it has some diminishing curve / inverse relationship to the size of the system.
