Not just that, also in the case when a big company acquires/merges with another big company. The suggestion to have loads of servers on a private range such as

Not just that, also in the case when a big company acquires/merges with another big company. The suggestion to have loads of servers on a private range such as e.g. 10.x.x.x is nice as it should be unique.. until this assumption breaks due to combining two networks together. It'll result in conflicts, discovery that lots of places had the IP address instead of a hostname, etc. It seems much saner to use IPv6.