Many enterprise programmers have to deal with lots of other programmers, who they may not talk to, who are of vastly varying skills. They might literally need to protect their code from someone else's misuse, so it can be fixed later if needed without far-reaching complications.

Which sounds a lot like an open source project, except that those involved may not be interested in what they're doing. I'd argue that makes them more dangerous, so a greater level of encapsulation may be warranted.