Ask HN: Is there something akin to “agents” in the software industry?

As a writer or an actor, my understanding is that you usually hire an agent who negotiates on your behalf, and you give them some percentage of what you make.

All of the job placement middlemen I've seen on the IT side of things are paid by my counterparty, and thus work against me when it comes time to negotiate.

From what I've seen, the difference between negotiating well and negotiating poorly is often quite large.

Does something like this exist for people in the "almost $200K/yr total compensation" range? Should something like this exist? What are the barriers to creating something like this?