[inferiorhuman]

  Netflix and Whatsapp can't be too wrong in their choice.

Most companies aren't Netflix, Whatsapp, Google, etc. Netflix can afford to run FreeBSD because they have staff that are intimately familiar with tuning it and hacking on the kernel. That's not most companies.

  No one said anything about entrenched systems that already use Linux or other systems.

GNU/Linux is entrenched pretty much everywhere at this point. Think about your stack. Does anything you use depend on GNU userland tools? Yeah, you'll get real good at rooting out hardcoded paths and dependencies on GNU extensions. Are your coworkers used to GNU tools? Well, there's a learning curve. Do you use nodejs at your company? The node maintainers actively refused to merge trivial patches to get current versions to build on FreeBSD (and the port itself stagnated).

Evaluating something that's not-Linux is neat and cool, I get it. But the reality is switching will incur a heavy up front (and potentially long-term depending on the candidate pool) cost and lots of long-term paper cuts.