This is because not all of the fonts can be used in every case. Therefore, only those fonts will be shown in the font selection box when working with a text document which can also be printed, as it is assumed that you will only want to use those fonts that you can actually have printed on paper.
例如，在编辑文本文档时您只会在字体显示栏内看到一些能够打印使用的字体。这种预置的用意很明显，因为您一般需要打印一个文本文档，也就需要使用能够打印的字体。