Hiring is _intrinsically_ a subjective act.
People are very much a moving target. They change over time. Work experiences, even bad ones, shape one's skills and ability to cope in organizations. Almost everybody has a bad-fit job at one time or another. The experience of a bad-fit is actually important to the growth of the individual and, I think, their coworkers and employers.
And the fact that we are able to do this while being blind to background (and open to people from all sort of backgrounds) is something that I think is very positive. We totally make mistake and reject good people. But we get better over time, and we also help lots of people get jobs they might not have been able to get without us.
That being said, there is a great deal of pseudo science being gobbled up by organizations because this is a mostly unregulated industry.
The most savvy candidates, however, tend to skip the step where you throw your resume into a giant vat with the others and hope for the best. Isn't it still the case that most jobs are filled using references and professional networks?
Even at smaller companies, however, there's some pushback to network hiring because it isn't particularly great for getting a diverse pool of talent.
To be honest, though there are a lot of dangers with this sort of thing, I am a fan. End of the day, engineers should be great engineers, not great at hacking the job finding process.
I'd be surprised if random resumes are really that much more diverse than network hiring. Consider principles like the Erdos number[1] -- the collaborative distance between groups of people in similar fields is strikingly small. I bet, a company with a reasonably large development staff (50 people) is probably no more than 2-degrees separated from 99% of the talent pool in a given region.
Just about every position I've looked at was with a company where a former colleague works.
What point is that exactly? Google, FB, Apple, Amazon etc all rely on their own internal recruiting departments.