Individual PCs my have been miniaturized, but the manufacturing process is certainly not. These days, the manufacturing of every single PC requires a global supply chain.
It's true that the mass manufacturing and cheap Chinese labor has brought the cost of individual computers down considerably. The energy required to manufacture an individual PC is also considerably less than the 1970's.
A more important question is this. What kind of technological inputs are required to manufacture a modern PC. Can you manufacture all the necessary components (starting with the microprocessor) and assemble them locally. I doubt if we can even manufacture an 8085 that way. It requires thousands of highly experienced PhD's and engineers to design, develop and manufacture a contemporary PC. Not to mention the huge advanced factories and large number of laborers needed in the manufacturing of every component. The demand has to be perpetually expanding for any operation to continue at this scale.