When have been women insulted for “being like a girl”? “Tomboy” could be insulting, though.

The “like a girl” ad campaign by Always was one of the first feminist campaigns (that I remember at least) to go viral: https://youtu.be/XjJQBjWYDTs

For a man to throw "like a girl" is generally seen as an insult.

Yes, but being feminine seen as something “bad” for women (which I thing was mlang23’s point) is much, much more recent. (I understand that women were seen as “inferior” due to some of those “feminine” traits. But I think they were insulted if they were not feminine enough, more than for being too feminine.)