Windows 10 won't boot off a GPT (bigger than 2TB) disk
Definitely a load of crap, it's quite happy with 4TB GPT disks from experience. I suspect it was a non-UEFI motherboard and the disk was actually MBR, hence the 2TB limit which is a thing for MBR not GPT.
I guess it might be just a case of them knowing how to set up disks with MBR, but not with GPT. And my point about preferring that they deliver something that works still stands.
Well, the mighty Goggle pointed me at a handy, concise, and CLEAR page on Intel's website that explains how to persuade Windows 10 CU or later to switch its infrastructure from MBR to GPT without nuking the disk and reinstalling. That makes me happy.
The most important part though is if it's correct.