I resent your sig, for I am the one and only dolt.

You haven't taken into account the premium that bidders at the barret-jackson auto auction will pay for this in 20+ years. Long-term future prices of collector cars are determined, at least partially, by their scarcity.

They're using this for their message passing, not their web stuff. For example, they accept tweets from sms, internet apps, etc. This system is used to handle all of those disparate messages in a performant manner. It's not about the calculation it's about concurrent message handling. Millions of people sending messages to them simultaneously.

From the Article:
Scala is different from other concurrent languages in that it contains no language support for concurrency beyond the standard thread model offered by the host environment. Instead of specialized language constructs we rely on Scala's general abstraction capabilities to define higher-level concurrency models. In such a way, we were able to dene all essential operations of Erlang's actor-based process model in the Scala library.

However, since Scala is implemented on the Java VM, we inherited some of the deciencies of the host environment when it comes to concurrency, namely low maximum number of threads and high context-switch overhead. In this paper we have shown how to turn this weakness into a strength. By dening a new event-based model for actors, we could increase dramatically their efficiency and scalability. At the same time, we kept to a large extent the programming model of thread-based actors, which would not have been possible if we had switched to a traditional event-based architecture, because the latter causes an inversion of control.

Read this and all will become clear:
Event-Based Programming without Inversion of Control

And get off my lawn!

The problem is that the programmers think they own the data when they don't. Your app will come and go and the data will remain. People will want to query that data, report on that data, or even transfer it into other databases. Database people think beyond the current requirements of your particular app.