> and which can be comparatively far more sinister and nefarious to debug.

This is kind of a false dichotomy as well written fp, type code is tends to have fewer bugs. Also your argument that more people understand it doesn't mean much as few people understand something they haven't been exposed to.

> hot-synching whole data centers

It actually does. There was a podcast with Paul Chiusano who is a big proponent of this type of programming http://futureofcoding.org/episodes/10-unisons-paul-chiusano-.... IIRC Spark is based on Algebird which is somewhat close to this type of programming. Commutativity is a life saver for distributed computing.