If I remember correctly, there's an ancient article by Joel Spolsky about this.
That great candidates are not out there doing blind interviews, only those of us who are average are interviewing and going through hoops. Engineers below average are almost constantly interviewing.
It’s rather older than this. Any argument about “the market is swamped by bad X in circulation and good X are much rarer in the market than you would naively expect” (software developers, online dating, used cars, debased currency…) is just a version of Gresham’s Law, which is 500 years old: https://en.m.wikipedia.org/wiki/Gresham%27s_law