It’s a funny cultural thing. Here is a caricature: Hiring managers have a real problem to solve: “how do I hire?”. They don’t have the time to conduct actual experiments and work out what actually relates to better hiring. So they trivialise the solution into some assumption about how the information captured in an interview generalises to overall suitability. They then proceed to defend the process and it’s results…
The ultra darwinian workplace is probably not a fun place to be. Also it sounds implicit in survival that there is some obviously fairer natural law that governs who survives. It's another judgement by someone with similar repeatability issues, albeit a judgement with more observation time (and more collateral damage to everyone else who is in fear of losing their job).
As far as “darwinian” goes some of us relish a meritocracy and loathe being surrounded by duds. I understand “Valve” to do something just like this but to a greater extent and they are not having problems hiring.