I imagine this comes with some credentialism and networking i.e. companies ask each other whether person X is good? If so, I can see how easily the current difficulties in the labor market can be overcome that way.

I don't have a CS degree, and I am talking about inbound recruiter emails, so it's not credentialism or networking. I did get my current job via networking though, but networking in this industry isn't really any more than "I used to work with this guy and he is good so give him an interview."