There's no conspiracy to push down wages - these are real complaints. The same problem exists in many fields - there's a difference between good people and qualified people. As a hiring manager, when I complain about finding qualified people, I mean people that can show, in an interview, that they're open to and reasonably good at learning. I've hired highschool dropouts (and am one myself) and PhD grads.
We need people that are in STEM because they WANT to be in STEM. Trying to get more people educated in a field by saying "we need more people with STEM degrees!" is like saying I need more people who know how to run. I don't want someone who knows how to run, I want someone who loves running.