Hiring's only obsolete while the stock market remains inflated and the cash keeps piling up. Come next recession, the deals will dry up like the Sahara.
Then again, come next recession, hiring will likely dry up too. So maybe hiring is obsolete.
The way Google does it, it's almost hiring, just with slightly bigger starting bonuses, and a different interview process. None of the normal trappings of acquisitions (integrations and fuck-you money spring to mind) are there.