[j7ake]

This goes to show how prestige and reputation built up over centuries can be destroyed in a matter of decades.

Also the prestige and reputation of institutions rest solely on the superstars that are in that institution. A single prominent scientist can carry the prestige of an entire institute. This means when they leave, the reputation goes with it.

[jltsiren]

It's about the institutional culture, not the superstars. The reputation that matters comes from a culture, where the people who are good at what they do can focus on what they choose to do. But if the government / administrators / donors / other politruks get too much say over how the institution is run, that reputation can easily be lost. Superstars leaving is then just a symptom of a wider issue.