It supports the idea that the cost of finding someone of similar criteria among the unemployed, or taking a less skilled programmer and investing in them, excee

It supports the idea that the cost of finding someone of similar criteria among the unemployed, or taking a less skilled programmer and investing in them, exceeds the cost of finding them among one's peers. That's not necessarily a consequence of there being an engineer shortage. You'd expect much the same behaviour if most people who emerged from uni, or worked commonly in IT, didn't have the criteria they were interested in.