For stuff that is still maintained but also legacy, military and contracting benefit from being a pretty insular community. Contractors are full of military retirees. What this does is give a pool of people who worked with the products for a very long time on one side who move over into maintaining them on the other, less knowledge is lost. It still happens and things must change eventually, but they manage to delay things where someone else like a bank might have a harder time when their knowledgeable employee leaves and they’re hiring people off the street.