Software Costs!
Even if you or I are are not clever enough to program in AREXX (Actually, its easier than BASIC, but don't let on you know!), others are writing little programs some of which you will find useful. Indeed, there has even been a trend among commercial developers to write AREXX programs to make their software easier to use. Others are linking word processing programs with desktop publishing programs with database programs and so on, but not necessarily through AREXX. As in real life, good communication is key.
Of course, some programs implement these functions better than others. Some can output to a postscript printer while others are limited to screen dumps of text which can produce poor results. Some programs have spell checkers that are slow and have problems guessing the word you were trying to spell. Others have thesauruses which would be inadequate for grade school.
Scalable, printable fonts allow you to scale text to a large size without getting "jaggies." This is because postscript fonts, unlike bitmapped fonts, are mathematical descriptions of letters rather than the letters themselves.
Without going into detail, conversion from mathematical description to flesh and blood letters is either performed by the printer, thus making it a postscript printer, or by an (Amiga) program, a postscript interpreter. Thus postscript can be output on a dot matrix printer once the document has been run through an interpreter.
Regrettably, some word processing programs require that you use their own proprietary postscript fonts thus limiting your choice.