no, but those those skills are important to have as well as feeling comfortable with a couple hundred pound machine between your legs. a dirtbike can help with that in a relatively safe environment. a dirtbike also isn't going to get hurt if it's dropped. a dirtbike can also teach you slow maneuvering and good bike control.That week of motorcycle class isn't to learn throttle control or how to shift
then when you have your license or are in the course those pieces become second nature. you don't have to think "how do i brake? which lever is the clutch? which direction is upshift?" that stuff just happens and you then learn to ride a bike on the street - learning traffic, how to anticipate other people, even things like signalling or headlights. if you've never been on any type of motorized bike before i think it's a good idea to get familiar with a bike by playing with a dirtbike before taking the MSF class or getting a bike of your own.
riding a dirtbike is in no way a replacement for the MSF course. it is a good idea to use one to get familiar with riding a bike and then you can use the MSF course to learn how to ride on the street instead of using the MSF course for both learning how to ride on the street and learning how to ride a bike