[nerdponx]

I think the question of "fancy technique versus simple technique" is beside the point. Assume for the sake of argument that you have a research organization and that it's worth your while to commit their time to a recommendation system.

The point here is that you don't typically need a huge amount of computation power to serve recommendations, even if the underlying model is sophisticated and required a lot of computation to train.

Likewise for data access, the online recommendation system typically does not need full access to the databases that the researchers need access to.