Rasa Server - Sanic

I see that Sanic framework is used for Rasa Server

Is there a reason for choosing Sanic over other python frameworks/server?

If I recall correctly, prior to version 1.0, flask server was used. Sanic is a drop-in (sort of) replacement for flask with async requests so, that may be the reason.

Our reasons for using Sanic is the same as anyone’s reason to switch to an asynchronous server. You can perform other tasks while waiting for I/O without using multithreading.

Are the libraries for the implementation of the tracker stores given out-of-the-box by rasa inherently async? I have a suspicion that they are not