This has been observed repeatedly, Fred Brooks wrote a whole book about it. Everyone says they've read and agree with "The Mythical Man Month" but when schedules loom the first reaction is always to throw more people at it. An expensive hot-shot added late in the project can grind the gears much worse than a green trainee.
A company wonders why their development team is performing and they decide they don't have hotshots, or need more "hotshots" they can recruit from whatever company they think is a good place they can poach from. Communicating to the team that if you want to grow or be promoted, switch jobs. So a lot of money is spent and chaos created to get the results that a solid, if not brilliant or terribly experienced team, could accomplish.