Bogarting unadvertised IPv4 space is common. A lot of people don't understand that it's not just public IP space that is in short supply in IPv4. IPv4 also has

Bogarting unadvertised IPv4 space is common. A lot of people don't understand that it's not just public IP space that is in short supply in IPv4. IPv4 also has inadequate space to number large private networks in a non-conflicting manner. Causes all kinds of crazy headaches with VPNs and distributed networks too... try linking two sites that both use 10.0.0.0/16 sometime. It's hell.