The answer, as best as I can tell, is commoditization. In our industry the middlemen – hiring managers, HR people, recruiters, etc. – work extremely hard to commoditize labor.
Why is this? I've seen it pushed to the level where it's clearly detrimental to the company... It seems irrational.
It's perfectly rational. The primary concern of the corporation is to remain a 'going concern'.
This entails certain operational risks, key of which is 'key person risk', where the ongoing operation of the business is exposed to the availability of a single person (or small number of people).
This is why CEOs of large companies are such mediocre 'everymen/women/persons' because if the ongoing operation of the organization depends on the availability of the CEO, that is a very large risk to be exposed to.
If you cannot reduce a function in your organization's business process to something that is repeatable and replaceable, then you have an ongoing operational risk.
Small companies value growth, large companies value security, consequently large companies will expend more resources on mitigating risks than expanding the market/revenue/products of their business.
Why is this? I've seen it pushed to the level where it's clearly detrimental to the company... It seems irrational.