Lets get straight to the point that this is just flat out not true. It's a physical impossibility. It never has been possible, isn't possible now and never will be in the future
You can also read about more dubious reasons in the 'little secrets' section
Tl;dr: Leader simply doesn't know what Follower will do or where they will go because the Follower doesn't know until they have done it. Therefore the Leader 'instigates' and then synchronizes with where ever the Follower is after they have done it. Everything else won't work.
Read about how it really works including the logic and other proofs
Now ask your instructor "in precise terms, how do I follow a lead"?