Et Tu Mary Poppins?

So, an English professor at a college is all upset because Mary Poppins in the movie is dressed in 'Blackface" because of course there NEVER were female chimney sweeps.

No, none during WW1 because the men were off at war....

 None during the Second World War.

None who took over their husband's business because he was too ill to work...

None because, well, it was a good paying job....

What is wrong with us in this country? Why are we just "looking" for stuff to be unhappy about?