The author works for a company marketing a "a scientifically driven way to quantify the match between a job candidate and an open position" and is making claims derogating another mechanism for matching candidates and position. He's not exactly an unbiased observer. For the record, I've been involved in hiring here, and I've never asked candidate who he knows at Google, I've never heard of a candidate being asked suc…
I suspect he may be conflating recruiters and interviewers to some degree, if one assumes he is being honest.
Recruiters know that an employee referral is more likely to yield a hire, so it makes sense they might use that to prioritise those people in terms of scheduling interviews.
It would probably only rarely affect the end result (and if so, only on really edge-case candidates), but it would affect the speed to getting to on-site.