I believe he means that if you cannot use an architecture where you push presentation logic to the client as JavaScrpt (aided by an MVC-like framework like Backbone), serve all HTML/CSS/JS statically, and serve data dynamically through a web service (e.g. node + express or express-resource, RoR or Sinatra, MS Web API or WCF), then it's important to know a modern (MVC-based) server-side web framework dynamically generating HTML.