Lets say you have ten support people, one has ten years of experience and the other nine have one year of experience each.
If all keep all knowledge to themselves the organisation would have 19 (experience-years * man-years ) as resource in total. (10*1 + 1*1 + 1*1...)
Worse, those 19 years of experience is not easy to use efficiently as nobody would know where to pipe a request or issue. "Who if anybody knows anything about this?"
Now, if the same team shared all, knew all, and used all, you would have 190 (experience-years * man-years) as total resource. (19*1 + 19*1...)
É claro que na prática estas coisas não são assim tão lineares, uma equipa de 10 pessoas, não passa de um factor 19 para um de 190 de grau de utilização dos seus conhecimentos, mas é esse objectivo (factor 190) que às equipas cada vez mais se exige.