What are the benefits of using get_template_part()?

Main – Loads a template part into a template.

The function provides a mechanism for child themes to overload reusable sections of code in the theme. So you have always the right path, file and a solid chance for developers, other code to change the result. See also this solid answer to a similar question.

But the magic behind get_template_part() is in the function locate_template(), which checks first the theme directory, then the parent directory (if one exists) for the file named. This is very useful for plugin development.