Pete Hunt addresses this specifically in this React talk starting at 3 minutes:

https://www.youtube.com/watch?v=DgVS-zXgMTk#t=182

Basically, the idea is that most JS templating solutions separate technologies (HTML , JS, templating languages), but don't actually separate concerns, because the concern is simply generating and updating DOM regardless of how many technologies you use.

Most JavaScript frameworks or libraries that handling generating and updating DOM, like Ember's two-way binding with Handlebars and Angular's dirty checking with directives, don't really separate markup from logic. They just invent a new language to mix with your HTML, and that new language is deliberately made extremely weak.