It is also clear that she
did not compose nearly as prolifically as her brother, and obviously,
the fewer works you create, the higher the chance that 100% of them will
be lost to time.
In short: I know you are pretending to “know why”. As usual with these kinds of assumptions, you are wrong.
“History forgot someone. It must be sexism.”
Plus she was not “erased from history“. I’ve been teaching my students about Mozart this month as he is our composer of the month and every bio I’ve used mentions his sister. As a music student I heard about her all the time. We know she was a talented musician we just don’t know her compositions because as the person above mentioned they did not survive to the modern era.