Because it’s reliable and Free. Free really means Free with an uppercase F. Free is more than just gratis (which is just a side-effect). It means that you are in control of your data and, if you wish, the code of your desktop publishing tool. That’s what smart individuals and companies prefer
Most proprietary DTP programs store data in binary file formats that can’t be read by most human beings. Some even encrypt their files to make sure that sure you can only access your work with their closed software. If such a file has been damaged, it’s close to impossible to repair it. Scribus uses a radically different approach, because its file format is based on XML, i.e. it can be read and analyzed by using a simple text editor. This not only means that you can repair damaged files rather easily; you can even create your own Scribus files without access to Scribus!
Creative desktop publishing without color is like cooking without spicery. Scribus is being shipped with almost 200 color palettes, and we will add almost 400 more for download in the next stable version. Most of these are commercial color systems, but the collection also includes national and government color standards or open source color collections. Scribus supports RGB, CMYK and spot colors and, most importantly, provides a robust and very reliable color management that leaves you in control of color display and conversion. Moreover, in Scribus you can emulate various forms of color blindness to see how your color choices affect people with color vision deficiencies.
Reliable PDF creation is the key to a successful print run at a commercial printing house, and it has been a pillar of Scribus development since the early days of its development. Scribus was the first DTP program in the world that supported the demanding PDF/X-3 specification. Scribus also offers a wide range of options with respect to PDF export. Issues with PDFs created by Scribus always enjoy the highest development priority and will be solved immediately.