Using whaat are traditionally opposite-gender names for newborns has always been around. Not a new thing at all. As you suggest, anyone who has expanded their tree has probably found cases of tht.
My most prominent one was my paternal grandmother and her nest two sisters (early 1880s) who were named James, George, and Elija. Apparentlly great grandfather wanted boys. But calmer minds added feminine middle names. so James (grandmother) was known as Jerrusha, Elija Ann became Elizabeth, and George Lula became Georgia. Grandmother named my father after her sister George.
We gave each of our girls 4 or 5 names so they would have some level of choice when they got older. No male names though.