Brian Marick:

So, interesting: an enormous amount of effort is spent on apps that convert map/vector-structured data into map/vector-structured data.

However, because of the mindshare dominance of object-oriented programming that came because of Java - “Smalltalk for the masses” - it’s hard for most people to think of an approach other than a pipeline of structured data -> objects -> structured data. The tools and frameworks and languages push you toward that. So: a programming model tailored to objects with serious lifetimes has been used for data that lasts only for one HTTP request.