MacStudent, I'll try to be a little more civil...
Certain applications can't work with OpenType fonts to their fullest extent. For example, the relatively common Microsoft PowerPoint can embed fonts so that a presentation file can be played on another PC, even without the fonts natively installed on that guest computer.
PowerPoint seems to like TrueType format to embed, not OpenType. At least, that has been my experience.
Thus the need to convert OpenType to TrueType. I hope that answers your question without me sounding like a total jacka$$.
JP