In my writing class, I was surprised to learn that ポイント can be used to mean パーセント in graphs. In English, we don't normally call percentage points just points. Does anyone have any background / insight as to when/where ポイント can be used in Japanese?
It's just a shortened form of "percentage point." Japanese is a language that loves to abbreviate things, and saying パーセントポイント every time could be unwieldy, and using "percentage points" is more accurate than saying "percent" when talking about increase if we're talking about a simple increase in a number of percentage points. For example, if we have 50%, and we say "It increased by 10%," technically that would make 55%. However if we say "It increased by 10 percentage points," it would be 60%, and that's where Japanese takes the usage from.
You can find some more details under 用例 here on Wikipedia.