It has the same amount of evidence as all these "hiring is broken [for the most profitable and transformative industry in all of human history]" posts.
If hiring in tech is broken, then all of hiring is broken, whether it's fast food cashiers or aerospace engineers. Can you seriously claim that any of those have better hiring practices? From personal experience, I can say they are far worse.
That's not the ideal response if you actually wanted to defend your claim about the internal data and special competitive advantage rather than just abandoning the claim.
Seriously, I would say that the competitive advantage of a company comes primarily from its product and the vision and competence of the company leadership. You can't just hire your way to success without that foundation. Bad leadership can destroy the greatest employees.
The company founders almost always come together in a very informal manner, and often the early employees do too. And that's the basis of the company. It has nothing whatsoever to do with some special snowflake data-driven formal hiring process.
Indeed, I would argue that once a company becomes very large and successful, they become bloated and bad at pretty much everything, including hiring. At that point they have to get better by acquiring other companies, not by hiring through their standard bureaucratic processes. The competitive advantage of giant corporations is the ability to swallow other companies whole.
Google basically admitted that GPA and where you went to school don't matter and do not correlate with job performance. And yet here we are still optimizing on the Ivy League. It'd be a safe wager that algorithm whiteboard interviews don't either except that they screen out folks who don't pass the interview. So because everyone has that baseline, that baseline is by definition meaningless. The other side of the coin is that performance management is also just as bad.
Work results are only sensible measure for the work performance. Easy hire and fire is one solution. Also a short trial period at the start of the work agreement should show if results happen or not (fg. 4-6 months).
I don't know if it was ever made public, I think I heard this story via backchannels. But Google did a research project at some point to discover why GPA/interview performance in general did not seem to correlate with post-hiring job performance. The project was never allowed to reach full completion because the direction their data and investigation was going looked like this:
"Our hiring process does not correlate with post-hiring job performance because we have a large and measurable bias in interviews in favour of Ivy League candidates and women."
In other words, GPA didn't correlate with job performance for Google because it was a confounding variable: they were selecting the sample for top tier universities (which select on GPA) at hiring time, but not when it came to promo reviews (which had a different process and anyway, less rhetorical ideology involved than hiring, at least at that time).
No, it's just the companies using it keep that data to themselves. Their hiring process is then a competitive advantage.