There is more to the real world than running webshit behind VM clusters.
Real businesses still run legacy file/print services, license daemons, proprietary applications. Some still run on bare metal.
You need outage windows. You can't just YOLO it and update prod during the day, it's unbelieveably irresponsible.
Well then, it's a business decision to accept the risks. IMO it makes sense that a percentage of machines would always be offline for maintenance. If you're running bare metal and you cannot afford 10% of your machines being offline at most times, then you're in deep shit if there's even a tiny traffic irregularity, and it's a sign that your management is YOLOing the company. Not uncommon though.