The tagline is definitely not about using node :) We include brunch.io, a nodejs asset builder, for our css/js building/bundling. Phoenix is first and foremost and Elixir web and distributed systems framework, which is where we get our productivity, speed, and maintainability.
> A productive web framework [using node] that does not compromise speed and maintainability.
CORRECTION:
> A productive web framework [using elixir] that does not compromise speed and maintainability.
Apologies for incorrect info, I saw the "npm install" content in the instructions and assumed it meant phoenix used node.