Did you read the linked article? Its part of a whole series of seven explaining exactly why that's the case.
They can't be assembled in the US. The issue is that because they're not the US lacks the experience to put it together. This isn't a matter of cost or anything, its a matter of process engineers with the relevant skills. They'll need training - why I say nothing for a generation. The US lacks the skills to make this stuff. Sure, we can say that's a consequence of outsourcing (actually the argument of the linked article) but that doesn't change the fact that it exists.
Saying "it would work" isn't an argument, Ruby. What makes you think it would. Trieste points out that your proposed idea would cost companies money, you're saying they should spend even more to build new factories rather than just shrugging and selling to the EU, to Canada, to Asia, to one of the numerous other markets. I'm not saying it wouldn't - I lack a whole load of knowledge to make that statement one way or the other - but a flat statement that it would is idealism not debate.
Another side issue is that I'm British and Ephiral is Canadian. We don't necessarily want more jobs in the US, we're not making our nation more vulnerable, etc. Try to remember other countries exist, and maybe calling people sheep, unpatriotic, etc isn't strictly appropriate.