Well you can blame Micro$oft probably.
and
https://en.wikipedia.org/wiki/Unified_Extensible_Firmware_Interface#CSM
particularly note:-
With the release of Windows 8 in October 2012, Microsoft's certification requirements now require that computers include firmware that implements the UEFI specification. Furthermore, if the computer supports the "Connected Standby" feature of Windows 8 (which allows devices to have power management comparable to smartphones, with an almost instantaneous return from standby mode), then the firmware is not permitted to contain a Compatibility Support Module (CSM). As such, systems that support Connected Standby are incapable of booting Legacy BIOS operating systems.[66][67]
As you will see that depending on the "firmware" implemented by the manufacturer,then it is designed to allow booting from CDROM/USB OR "legacy" HDD's. If your machine has a broken implementation and only supports the MS hegemony and has no or incomplete CSM code then maybe you're screwed, so yes call them on that maybe they have a fix. . .
BUT, most of those disks I linked to DO include compliant GPT/EFI boot loaders. If not, any of the many current "live" linux distro's (debian,BSD or RH based) will prove that point as they all also do UEFI booting on most anything.