Of course one device can be tracked. But not every CPU can be tracked, I consider that quite infeasible indeed. If you already know the target, and know that target is looking to buy a new PC/laptop, you can feed it a specific CPU, sure. But you could just as well feed it some sort of modified BIOS that doesn't require any special hardware, and would be pretty much just as hard to detect for someone that isn't specifically looking for that kind of modification.

But that's usually not the interesting case. The interesting case is that you find a new target, and that target already has a PC/laptop, and you want to gain access to it without having to physically infiltrate. Now, you might be able to manipulate their network in some way, or send them an E-Mail, or get them to visit a website that contains an activation code. But having to backtrack which CPU that laptop contains seems impossible to me in the vast majority of cases. Even if you can somehow figure out where he bought it, most stores aren't even going to be able to tell you the serial number of the product they sold, and even if they can, now you have to match that serial number to a CPU, which is... impossible? How would you get that information? Retailers buy hundreds of thousands of CPUs, and they probably don't tell Intel which CPU they put into which device, or even who buys which individual CPU. If you send a CPU back on Amazon, they don't even check if it's the same goddamn model! (Hence the surprise of some people who bought a $550 CPU and got a $550 CPU box with a $50 CPU in it.) And if the CPU or laptop was bought used, now you're really out of luck. I really don't see how this is very useful, when instead of doing that you can just force Intel to give up plausible deniability and hack everything in sight. If you get caught (which is incredibly unlikely in the first place), you just say "we did it for America!" and that's it, nobody would care. I mean Intel would be kinda fucked, but the NSA wouldn't be.