There are only 24 hours in a day. Management teams only have so many hours to do their jobs. Every time we give them a new responsibility or special project we are either forcing them to work more hours or to quit doing something they are currently doing.
Most people substitute a new activity for an old activity, rather than increase their work day.
Unless we as management do a cost-benefit tradeoff before we assign the new responsibility or project we may be shooting ourselves in the foot. We all know people are the most effective and provide the best return on our investment in them, when they do the things they know best and do frequently. Let's take recruiting to fill a new position as an example. Sure, anyone can do recruiting. When your people spend time trying to find management people there are two types of cost.