Package managers allow to install easily and update dependencies of the project - basically third-party libraries that it uses: jQuery, Fotorama - so everything that is used on your website and written not by you.
You can replace by few commands in the terminal a lot - surfing the web sites with libraries, downloading and unpacking archives and copying files to the project.
From above mentioned is evident that at least understanding of Bower is quite useful. We have learned in details how to use Bower on our internal educational evening in Deweb Studio that led Volodymyr Puchkov our Front-end developer.
The details are in the presentation under link.