It wasn't millennials who started that one. I heard it from my genx history teacher. Who honestly I had a lot of respect for at the time, maybe because he told us stories like that, but the more I learn about the world the more I find he was so full of shit and he was like my favorite teacher so its disappointing. One of these days I'm going to find out that the Maginot Line was actually a great idea and if you are France after WW1 you should always build the Maginot Line.

Re Catherine the Great's horse thing, my understanding is that the stories were contemporaneous with her rule and that all powerful women in europe had similar sorts of things said about them. There as a whole early tabloid industry describing in detail the various imagined exploits of Marie Antoinette.