Relationship between a desired attrition and incidental attrition.

When I look at how attrition has been categorized, I see two ways, if not more; voluntary vs. involuntary and functional vs. dysfunctional.
Up or out philosophy vs. life-time employment firms, rare skills and hard to build competencies to average operations skills, what suits your business and structure can be very different. Company A's top performer joins company B and here he becomes a poor performer and then he moves out or is shown the door. Puzzling to categorize this attrition. Attrition driven by culture and business and people values? Lot many companies wish, their identified laggards and petered out (On whom Peter Principle has applied) leave but they remain there, creating glass ceiling for a performer and then he quits looking for a place that provides growth opportunities. Here I see a relationship between a desired attrition and incidental attrition. All companies would agree that their desired attrition shall be 'x' percentage, identified by stack ranking people and then planning a counsel out approach for them. Look at how Microsoft has planned for 18,000 people over span of 2 years. This gives a clear idea that companies have a 'Desired' rate of attrition that is expected and worst comes that when this does not happen 'Incidental' attrition takes place where people who want to move up and want to work with smarter set of people, move to a smarter and progressive company that follows 'meritocratic' culture. Incidental attrition sometimes takes place within weeks of joining. I have normally categorized attrition into 2 brackets; Induced by internal factors vs. triggered by external factors. Simply put, "to get out of here' vs. 'to get in there'. There will always be companies for good people. Good people need good people. Other type of attrition is 'aspiration-led' attrition. Here I have seen employees jump 3 companies in 2 years or less. Market inequality creates attrition due to its own brand value that simply means, better standing in society, better pay and benefits, lots of other privileges. Can we blame any company for being so rich and fancy causing attrition at other places? Can we blame a company for been less rich and not providing high-end benefits and social/corporate standing or ‘prestige’ as says is a reason for ranking consulting organizations by employees or candidates.
Voluntary attrition highlights what is ‘ignored’ in the organization as well as what is made available by competitors. All a matter of choice and decision of leadership.