Maybe the art of slipping has been lost. If you are too high of fast, slip. Maybe some pilots are scared of slipping because some POH's warn against with flaps extended it eg C172. I was taught it is not a structural issue, but controlability if you get too slow. Is this correct? 172s come down quite nicely with a boot full of rudder. Or are people's feet forgeting what those things on the floor are for?