I would agree in case of Manor, Minardi or any other new team, but after managing a team in Williams area I disagree

Sure it would have been lovely to re-hire Newey but I was not in a financial situation to do so, even with less talented designers AND no-name youngsters the financial situation was not in an area to keep anything close to a balance between need to stay (not actually get better)
Finding new talents is possible, but time consuming and takes a long breath. And once you found the gems you are in danger to loose them to Team Destroyer, Lotus and so on cause you can not afford them when the wages are continuously increasing exponentially.
edit: on the bright side, enormous wages/bonus might ensure that the overall balance of talented staff is not bundled into one, or a handful of teams - so finding the correct key persons to ensure success + upcoming and cheap staff is the option to go for