There are some surprising places where you can enforce state where it seems impossible. Once you have that, the benefits coalesce.

That's why I built ShutIt, which we've used to encapsulate complex legacy environments to produce stateless builds:

http://ianmiell.github.io/shutit/

For example, teams can have a development environment (with _everything_ in it) rebuilt daily. As everyone uses it, everyone curates it, and they're all talking about the same thing - one pet if you like, rather than n, where n is the number of developer/development envs.