The important piece of information that article is missing is that the PC isn't "Amazing" until you overclock that $75 CPU over 4GHz. I have a similar setup (with a better Z87 motherboard) in my MAME cabinet that overclocked to 4.5GHz. You can see MAME benchmarks here...
The "Amazing" part is that you can build a system so powerful with so little money. If money was unlimited, you could definitely build a better PC.
Also, the info is a little out of date. I'd definitely go with a GeForce GTX 1050 Ti 4GB video card for $150 instead of what they suggest...
Most modern PC games lean HEAVILY on the video card, so you can get away with cheaper CPUs if they're overclocked. Some newer games are beginning to really take advantage of quad core CPUs (and higher core counts) so in those cases, having a dual core Pentium G3258 is going to hurt you.
GroovyMAME support forum on BYOAC