Some are only available via subscription too, and you may not be able to download and keep them all. One thing to note about desktop publishers is that they can be expensive, especially if you want the professional software like inDesign.
And while they're often a little more complicated to use than Microsoft Word or Google Docs, they produce far superior results and are designed to help you print off the result effectively too. They differ from graphic design software because they're focused on the creation of a coherent page of mixed media, which is just as likely to focus on words as much as images. The best desktop publishing software packages all provide you with the tools to make your text and images as clear, well-designed, and glossy as possible.