I run a small manufacturing company so I have first hand experience that says yes, having access to domestic supplies of critical components is a massive competitive advantage against similar businesses in other countries. It doesn't matter if your product is for export or domestic consumption so this is a moot point.
This leads into your other point about offshoring - which by the way is the first time I've heard described as a "populist term". There are not too many countries around the world that have a large well educated populace, excellent transport links, reliable electrical/gas/water supply and domestic supply of essential high-tech components. The US happens to be one of these countries so establishing high-end chip fabs there does make sense. Salaries, labor laws, EPA regulations etc. in Taiwan are not massively different from the US and the EPA laws are actually stricter than most US states but Taiwan still manages to be a chip manufacturing powerhouse.
Africa is a nonsense comparison because the infrastructure just doesn't exist to set up a large high tech manufacturing base. If at some point the infrastructure is built I'm sure that offshoring to Africa will start to happen.
As far as the Chinese Market goes this is a grossly misunderstood and over-hyped beast. Western companies are very slowly understanding that there may be a lot of potential Chinese customers but it's very difficult to actually make any money in the mainland China market and even very large businesses are likely to get screwed at some point. I personally know of several American businesses who are pulling out or already pulled out of China and are moving back to the US.