The answer is simple - blame Sinofsky.
I don't blame Sinofsky - but then, unlike a lot of the enterprise users, I also liked Windows 8 as it was.
In fact, I just added another Dead Hardware Express PC that is now running Windows 8.1 ProWMC - the difference is that this one is portable. It is also the oldest PC - of any sort - that I have installed Windows 8 x64 (or 7 x64 for that matter) on.
The portable in question is the HP Pavilion 9700 Altec Lansing Edition. (This is the portable that the Envy with Beats Audio replaced in HP's portable lineup.)
This particular model has an AMD Turion x64 CPU, a decidedly atypical nForce Mobile chipset (even then, nForce Mobile chipsets were uncommon in Turion-driven portables), and a trainload of portable-media options - which you would need, as the typical HDD in this media-driven notebook is all of 150 GB (including restore partition).
Despite the age (it's older than the tower PC I just replaced the motherboard in), I had no problems at all getting it up and running with 8.1. (None whatever - I actually started with the notebook in wireless - not wired - mode; I couldn't have done so installing Windows Vista, for example - and that was the original default OS.)
The super-small HDD doesn't bother me - I'll be using this portable as an e-mail and workbook portable - the porkiest application going on it is Microsoft Office. Besides, if I ever feel cramped, I CAN always throw a 512 GB Crucial SSD (either MX100 or m4) in it; either one is no worse than $200 retail. (To put the size in perspective, that is three times the size of the HDD it came with.)