Many if not all FAANG companies supplement their workforce with those consultancies though. It's why I've stopped publishing profit per employee comments -- the denominator is arbitrary.

The truth is more complicated. Because these agencies have gamed the system, they effectively control some fraction of the labor market. To a degree, FAANG has to come to the agencies if they want engineers, no matter where on the experience / skill curve they land. I imagine there's also an element of reputation shielding as well -- people like yourself blame Tata instead of the companies that hire them, but the companies that hire them get cheaper labor that basically can't hop jobs. That has to be valuable, given the policies Steve Jobs shopped around for around no poaching.