Why is Polymer just a series of HTML files with JavaScript? -

i'm starting experiment polymer 1.0, , noticed of files included via bower broken following three:

• polymer-micro.html
• polymer-mini.html
• polymer.html

and each file imported via html imports within next 1 down list. then, rest of file javascript.

perhaps, it's lack of knowledge regarding html imports, clever way utilize dependency management javascript without having add third-party library browserify example?