As a software engineer: I've been chased by recruiters while heads-down on a project. It's an annoying distraction. With the tools at my fingertips (glassdoor, social and professional networks of other engineers that aren't particularly restricted by corporate borders in a deeply-interconnected era), I know the market value of the job and I know who's willing to offer more and less; I also can know about the corporate and engineering culture of the other companies. In short: if I want a change, I know where the door is and I know who's hiring. While in general, I'd agree with the notion that decreased price signalling could depress wages, I think it's a stretch to push software engineers working at the listed companies into an "oppressed workers" mold; it's a notoriously well-compensated field.
It's certainly a booby-trap to reason from one's own experience. But I find myself thinking that software engineers themselves might welcome the idea of a "no cold-call" list.
I've even had recruiters call me on my desk phone at work trying to do a sales pitch.