Even if every employee was equally competent, decision making needs to be consolidated enough that it can be decisive and shared throughout large companies. Complex systems that need to change rapidly gain no benefit from having too many people wanting to make decisions, you only need most of them to be competent enough to complete the work based on the decisions of a small group or the work will end up getting too convoluted and unmaintainable.

There really isn't a benefit to have everyone understand all of the parts of a large and complex system, if they only have time to work on a portion or to facilitate decisions that take into account the knowledge of the people in the different parts.