There is also a bit of strategic, defensive hiring that happens, i.e., hiring people so your competition cannot hire them, let alone at a lower salary if you were not hiring. It's a little talked about issue, because it is mostly expressed as a type of C-suite FOMO tied to their performance and stock option incentives, i.e., "we need to hire because X is hiring and we can't look like we are not growing/hiring because that will drive the stock price down and risks my stock options, even if we are doing massive buybacks to glaze the stock price".

It is another significant flaw in the "capitalist", i.e., publicly traded corporate system that incentivizes all the various financial shenanigans to generate false stock performance to enrich the c-suite.