This was about 2012 to 2014.
The page is long gone now but I definitely saved a copy because it was so blatant. Don't know how easy I can find it. May be on the Wayback Machine.
It had recently become possible to bypass Windows 7 activation using "Windows Loader" (by DAZ), a sophisticated hacker tool which loaded the proper BIOS hardware key[0] not from the mainboard, but optionally from a replaced MBR sector 0 on the HDD which then pointed to a file containing a copy of the original sector 0, from which the non-W7 MB then could boot W7 normally without needing activation.
GPT as "standard" and UEFI with Microsoft SecureBoot were then rushed out in time for the W8 release. Therefore almost all PC's newer than the ones "designed for W7" would require not only a complete HDD refomatting, but a more extensive complete repartitioning (MBR-style) before anyone could even try to install W7 or anything else other than what the PC originally shipped with.
Seemed to me simply to make it more difficult to install W7 on all future PC's, which would turn out to be the main competition for W8 after all. Linux was not as much of a threat, but the collateral damage was not unintentional and set Linux PC and dual-boot approaches back at least two years.
Now there is supposedly a hack that allows W7 to be installed on GPT volumes.
One of the Microsoft claims was that one of the security "deficiencies" of MBR HDD layout not found with GPT was the unused sectors which padded the area from sector 1 up until the first sector of the first partition which is the partition's boot sector (usually up to sector 63 but at least sector 32 and sometimes 1024 or more). This normally unused area between sector 0 and the first partition's boot sector was a good place for GRUB to routinely use for its bootloader but had also been a location for the occasional "rootkit" that could not be removed by reformatting or often even repartioning (you would have to zero that part of the HDD using ordinary non-Windows tools, like a disk editor or dd in Linux). Also an optional location for Windows Loader. "Benefits" of GPT was that no sectors are unspecified, true but in practice sectors 5 through 31 are still never used unless you have created more than 8 GPT partitions on the HDD. You can also leave as much space in between GPT partitons as you would like (this is not the factory default), and Windows built-in tools can do the job.
If you were on top of this and had a plain MBR mainboard with protection from flashing the BIOS, there was no way the mainboard itself could contain any kind of malware. If the HDD was clean, or fully zeroed, you were fine.
With UEFI systems, which contain much more extensive and flexible firmware you were actually more subject to nefarious actions if any could be devised, which could then reside in the mainboard along with the UEFI firmware regardless how thoroughly you zero the HDD.
This seems to have now become possible, maybe with the recent leak alone.
With the slyly undocumented proprietary UEFI firmwares, it is also not too easy to know if "updating the BIOS" actually clears any possible malware that might be still lurking there along with the new factory firmware you put in.
As far as I know there is no routine malware scan to check for compromised UEFI firmware like there has been for decades with HDD's.
UEFI seemed to be very dependent on highly secret firmware keys never being revealed, otherwise I expected a UEFI MB would then be compromised in a way that BIOS MB's could not, and potentially much more difficult to detect & remove.
[0] factory key code for the Windows version that originally shipped within a W7 PC mainboard BIOS so it would not require retail-OS-style activation, could then be used to freely activate W7 on older Vista PC's and expected to function on W8 PC's to come if they had regular traditional BIOS and MBR HDD layout. Almost like they knew in advance that W8 PC buyers would massively prefer to install W7 if they could rather than the original Windows 8.0.