The lines between "desktop publishing", "word processing", and "typesetting" seem kind of blurred to me. Modern office suites like LibreOffice should probably be considered desktop publishing software. Typesetting software like LaTeX, troff, and Lout have the same layout capabilities as programs like Scribus, but they just lack the WYSIWYG interface (which seems to be a requirement to be "desktop publishing"). So in that sense something like LyX
comes a bit closer.
In my opinion the distinctions are not that important, since in all cases the output is similar. The user interface seems more a matter of taste than anything.