In the past, as a hiring manager, my best hires by far came from a recruiter that I trusted. His hit rate was amazing. He spent hours interviewing people himself and by the time they came to me for an interview, it was because he already knew they were qualified.
In a world where people jump every few years, hooking up with someone like that seems like it could work out well, if they've built up a decent reputation. Basically like a good contracting company, but for FTE. Instead of multi-stage interviews at 10s of companies (or more), everyone on both sides of the process could save a lot of time and get down to the nitty gritty.
Just spitballing. I am only halfway through my cup of coffee, however. And clearly things like this have been tried, but always on some kind of large scale, which in turn destroys the effectiveness -- because it gets gamed, I'd guess.
But at a much smaller scale, does it work, do people do it?