isn't the TCO for those engineers also something like 400k each? not talking Principle Big-Dick Super-Staff Engineer, but like mid-level.
Netflix was famous for that, too -- no RSUs, just straight cash, and we'll fire you if we think you can't deliver.
100s of devs would essentially be their entire, company-wide, operating budget; it's gotta be like 10-15 people tops on these things.