The upper level managers don't pick the people who go. They pass the task down to the appropriate group manager to pick someone and those people pass the task down to the immediate managers to pick the person to go from the group.
Those lower level managers are incompetent idiots with severe ego problems. They keep the other idiots around them that never question them and get rid of the people who know what they are doing, because they are a threat to the manager's ego and a threat to the manager's yes-men.
So long as the incompetent management is never replaced, they will continue to get rid of anyone who is an immediate threat to them. They are not thinking long term, they are just thinking "who makes me look bad" at the moment.