To do it enmasse, you need lots of space. Like, a lot... Every year, when you review your expenses, you need to defend why you are spending millions for maintai

To do it enmasse, you need lots of space. Like, a lot... Every year, when you review your expenses, you need to defend why you are spending millions for maintaining a large pile of rubbish in the vague hope that one day you will spend other millions to dig into this rubbish and not earn money from it but send some bastard to jail. So, it must be either national security issue, or other long-term valuable information that is worth paying to have chance at cracking.