True, but that doesn't necessarily mean that there are large, unoccupied routeable blocks within their allocated ranges that those organizations could easily ha

True, but that doesn't necessarily mean that there are large, unoccupied routeable blocks within their allocated ranges that those organizations could easily hand back. More likely, they've got some sparse set of addresses scattered all over the place, reflecting allocations to their subdivisions. Hey, it's 1992; why not give that research group a /16 if you've got the bits? There's no immediate need, but they might use some fraction of it eventually. And they parcel out /8s to subgroups, a few at a time, averaging out to maybe a dozen machines (some groups with more, some with less). Upshot: in 2011, there's an internal /16 with a few hundred machines on it --- but reallocating it to a smaller CIDR block which reflects actual usage requires negotiations up and down the hierarchy. And this kind of cruft has been piling up all over the place for decades; sorting it out may be hard enough that some of 'em would rather fight than pull the switch.