Having a secondary or tertiary computer isn't a bad idea, be it for splitting up processes or putting computers in multiple rooms. That being said, if you have the hardware for it you should probably use it to your advantage for gaming on your current computer. For me, my secondary computer was built using spare parts, and I use it as a Linux machine for coding, web access, and even mid-level gaming (I put a less than $100 AMD card in it, and it still runs programs like Second Life on High graphics with little-to-no hiccup, along with steam games developed to run on a Linux platform).
The best part is, it's still a custom computer, so if down the line you maybe want to set it up for LAN games with a roommate/partner/guest, you can always upgrade the components (Just don't cheap out on the motherboard and make sure your PSU can handle the more demanding hardware). Just keep in mind that due to how often new technologies and architectures are developed in the hardware industry, prices will fluctuate; chances are good that the hardware for this "Boson" computer described in that article from July may have better components at cheaper prices by now. As long as you know what you're doing (and I've run into just as many people who don't as I have people who do), you can build and upgrade computers for whatever your needs may be.
EDIT: Something I should mention is that I personally don't trust the author of the video, as some of the thing's he's said in other videos just aren't accurate (for example, do NOT waste your money with windows 8; it's a great OS for tablets because that's what the architecture was built around, but it's a horrible OS on Laptop/Desktops. EVERY person I've known who had windows 8 on a non-tablet device has had it completely **censor** itself (meaning the only fix was to re-install the OS, loosing their data most if not all of the time)).