While I totally see where you're coming from with this (and agree with the sentiment!), it's not entirely true.
Yes, recent consoles (especially Sony and MS) have been using exactly PC parts, sometimes with minimal modifications.
But older consoles (and still Nintendo to a degree) have always used a completely different set of parts from regular consumer PCs.
For most of history, consumer PCs have used x86-range processors, while consoles tended to use MIPS, PowerPC or ARM based processors. These have some fundamental differences that make for a completely different experience. Sound and video hardware were often custom-designed for the specific console as well, and not something you could simply put in a PC and have it operational (though the video chipsets were/are definitely closely related to the available PC versions). And yes, Mac used PowerPC for a while as well, but a completely different type than was found in consoles.
So... while what you're saying is still true, your reasoning behind it isn't sound. Generally, in the past, equivalent/identical PC parts and console parts weren't available at the same time for consumers. (Of course, I'd say the biggest difference is the operating system, but that's an entirely different discussion altogether.)
You're limiting your range of what constitutes a PC (personal computer) to IBM-Compatible x86 computers when, throughout history, people have used a variety of architectures. Even the IBM-Compatible standard, what we consider a "PC", isn't that restrictive.
As you yourself state, Macs have only recently switched to x86 - they formerly used PowerPC, the same architecture that powers the Gamecube, Wii, Wii U, the Xbox 360 and, to a certain extent, the PS3, and it was not a "different type" at all, the console versions were simply customised. The PowerPC CPU's in Nintendo's consoles are in the exact same PPC7xx family as the PowerPC in the Apple iMac G3. In fact, initial Xbox 360 demos were actually ran on two Macs connected into one unit since it was easier to demo the software this way. I already mentioned the NES which uses the same family of CPU's as the Apple II, and while we're at it, the Ricoh 5A22 that powers the SNES is also derrived from the same family. The Z80 is another processor popular in both consoles and personal computers, and then there's ARM CPU's which not only power your portable consoles, they also power your smartphone, which is effectively a portable personal computer. "PC" in the sense of an x86 IBM Compatible personal computer didn't even exist until the mid 1980's and wasn't proliferated until the 1990's, before that the PC space was the wild west, so it's your post that's misinformed.
All console hardware is customised, but it stems from the same roots. Console manufacturers order customised parts for a specific purpose, but those parts are using the exact same technology as personal computers, servers and workstations do, they're just designed with a specified purpose in mind. There's no difference between a custom CPU from 20 years back and a custom CPU today, the principle is the same.
I feel that you're misunderstanding my position - I'm not saying that you can build all of those consoles with off-the-shelf components - you rarely can. That being said, they do use the same technology, they simply have a custom internal structure and use different elements on-die. You can't build an Xbox One or a PS4 with off-the-shelf components either, so I don't see the difference - both contain customised hardware that's unavailable to the public. With that said, they both use microarchitectures that are. Naturally the manufacturers themselves will sometimes design special sauce that they want baked into the die, but that was as true in the past as it is right now.