We owe a lot to those who work on package managers and the packages, but he has a point in that if it works so well it has a lot to do with the software being free.

Important things like good and efficient dependency management and library reuse are far easier to achieve when all the relevant sources are available to packagers.

IceWeasel and Chromium visually are Firefox and Chrome with different icons and you'll find them if you search their "real" names in the package manager. Not so hard, right? You can find about why they exist if you are interested, it's not required.