not only that...
"the problem with this is that there are only so many of those required."
No, that's not the main problem: we still *need* those "low-value" stuff, like T-shirts, cars, trains, screwdrivers... If they are manufactured elsewhere, we need to *pay* for them. If they are manufactured locally, they are part of the local economy. In other words, if you buy low-value stuff locally, the local community keeps the value (however low-grade) but if you buy it from abroad - because it's too low value for wannabee technocrats - the local community looses that value !
The point is, and Tim Worstall on CommentIsFree for the Guardian does this sort of lazy articles all the time, if you outsource manufacturing that you *need*, it's a *loss*. And if you pile up losses, over decades, you end up bankrupt. Plain and simple.