It's in the same sense that PHP is a programming language -- Django has its own idiomatic templating language with loops and other such constructs. It looks like this:

    {% extends "base.html" %}
    {% block title %}My amazing blog{% endblock %}
    {% block content %}
        {% for entry in blog_entries %}
            <h2>{{ entry.title }}</h2>
            <p>{{ entry.body }}</p>
        {% endfor %}
    {% endblock %}

As for why this thing can't recognize "it looks like HTML + JS", I can't answer that for you -- but there should be a family of responses; "HTML + PHP," "HTML + Django", "HTML + JS" etc.