I think this is a good theory. I almost wonder if it's an accidental synchronization of a burst of hiring caused by the FAANGs snatching candidates away from their peers and having outsized psychological impact.

Classically, the way to go from l1 manager to l2 manager to director, senior director and VP was to grow your organization in headcount terms, so in a situation where it is "hard" to hire, say Amazon is busy grinding through the entire valley, you might accidentally create a situation where everyone feels urgency but no one feels backpressure.