As with all the shiny toys that are available to developers, package management begs the question: is it worth it? Adding package management in any form undeniably adds another layer of complexity to a project, and as we all know, complexity is the enemy. So it's worth thinking good and hard about whether a project really needs any of the tools covered in this chapter.
If you work alone, and your project only uses a handful of libraries, ones that don't have a complex dependency graph of their own, then there's a good argument for keeping things manual. Changes in the tools won't affect your project, changes in the libraries can be updated manually, and you know exactly what's going on all the time.
If you work in a team, or a large project, that already uses some form of package management, then you have no choice, you need to follow the pack. If you need a proprietary framework that is only available through a package manager, the same holds true.
And between those...