You're right, pure REST is very academic. I've worked with open/big data, and there's always a struggle to get realistic performance and app architecture design; for anything non-obvious, I'd say there are shades of REST rather than a simple boolean yes/no. Even academics have to produce a working solution or "application", i.e. that which can be actually applied, at some point.
When there is lots of data and performance is important, HTTP is the wrong protocol. JSON/XML/HTML is the wrong data format.