I mean, “Masses of workstation class audio rhythms and the simplest way ever to arrange, all in a mobile app?”  How is all this possible?

Well, if you are interested in the technology behind Alive Drumming’s Smart Web Services, even though it has very little to do with Music or Musicianship.  http://alivedrumming.com/alive-drummings-smart-web-services-with-elixir-phoenix-and-gcp/  You find it interesting if you are into in computer programming and building highly reliable web services using Ericsson’s Open Telecom Platform (OTP).

Alive Drumming’s Smart Web Services with Elixir, Phoenix and GCP