> Unless you dangle HEFTY stock options with incremental maturity dates

That is indeed how this whole thing works. I used to work with several folks who were kicking around FAANG for 4 years till their acquisition stock fully vested

When you consider how much time/money it takes to hire an experienced engineer, and how quickly they are liable to jump to the competition, acquiring an existing team of experienced engineers and tying them with the golden handcuffs is not a bad deal