What's their basis for concluding that 'CPUs will be presoldered to the motherboard' implies "PCs have no relevance"?

Intel Atoms come presoldered too. I admit to finding that change a little disappointing, but not Earth-shattering.

I've been replacing chips since the original IBM PC, so I consider myself an 'enthusiast'. But I can count on one hand the number of times I've upgraded my CPU without upgrading the MB and RAM too. When building new systems, I always buy the CPU, MB, and RAM from the same dealer on the same invoice to avoid any ambiguities with compatibility returns.

And I'm part of that weirdo fringe who builds our own systems. I wish it were otherwise, but consumers who prefer to insert their own CPUs into MB sockets have never been a particularly large part of the PC industry.