Apple Fitness+ fast forward / rewind?

Why can’t you fast forward to preview, or rewind to do something again? I use fitness videos on YouTube and Les Mills Online and use these features all the time. My internet sometimes cuts out and there’s a lot of buffering, the rewind is pretty essential. And the fast forward is not essential but extremely useful when you want to preview a workout to see if you want to do it. These are pretty basic features, seems very strange they’re not available, why not?