It's news b/c tech companies doing it recently as a precursor towards layoffs. I know my area did it recently with our contract employees b/c we got our funding cut. As long as we had funding we were hiring more & rarely got rid of anybody, even crappy employees simply b/c they could at least do enough to justify their pay. But once we had to reduce team size or number of teams, stack ranking came out & the bottom rungs got cut.