Did you even read my comment? It's quite clear what your environment was in the data-centers, with spares and remote hands.

Mine wasn't and then I say three months I don't kid or jest.

> No problem to put /boot on a raid1 on a small partition across all drives

This is exactly the problem. If the drive isn't totally dead (like it doesn't even respond to IDENT) then there is a chance what the BIOS/UEFI would try to boot from it and even succeed in that (ie would load the MBR/boot app) and then there is no way to alter the boot process at this point. HW RAID card provides a single boot point and handle the failing drives by itself, never exposing those shenanigans to the upper level.

Like sure, you are happy with your setup, you never had a bad experience with it, you always had OOB management and remote hands - but it doesn't means what it a silver bullet working 100% of times for everyone.

Yes, I've seen systems with SW/fake RAID failed to boot because the boot process failed after selecting a half-dead drive as a boot device, with my own eyes. Thankfully I was geographically close to them, not 5000km away.

Yes, I serviced and prepared systems for the 5000km away divisions and they are really serviced only a couple of months in a year, all other time you need an extremely urgent reasons why do you need to a rent a heavy 'copter to go there. No, there is no remote-hands there. The maximum point of IT-competency there is raking bills with satellite Internet.