Most of the women I know well enough to know this about them track and predict the onset of their next period without needing an application. It isn't exactly rocket science.
1-2 generations? give an advanced anything to anyone with no true knowledge of how to do it without the tool and you'll have people fully dependent in hours.
kids today cannot navigate without turn-by-turn. nobody looks at the map to get names of major streets, they just blindly follow the directions. I learned how to navigate as a kid just by being bored and staring out the window and being able to recognize things. Now, kids don't even look out the window as they keep their heads down and eyes glued to a screen.
This is a strawman argument. Nobody is arguing that period apps are a necessity. Women have been tracking our periods without computers since prehistoric times. Women were doing rocket science calculations before computers, for that matter. Of course we can do without period apps. But they're more useful than any other health tracking device or app that I can think of.
