Managers are rewarded and promoted based on everything they & their team "do", not on what they "undo" or "don't do"
So manager x adds 10 things to the website, gets rewarded and moves on, then their replacement adds 10 more things, gets rewarded and moves on etc.
It's in the interests of those managers future careers they don't allow anyone to remove the things that were added during their reign, otherwise the list of things they "did" won't be very impressive.