Earlier quoted context omitted.
That's exactly as saying that someone made a full c++ program using nothing but notepad and therefore it's impressive. All I see its someone that made their lives more difficult by purpose.
I think you fail to appreciate that learning a new skill requires some kind of connection to an already learned skill, and that this connection becomes harder to establish at old age. The old lady's choice may have made perfect sense from her point of view.
Pretty sure whatever she knew already (e.g. oil painting) at least had anti-aliasing; what I mean is that there are tools that are even simpler than MS-paint but produce better results ("better" as in art more likely to be liked by more people)