you dont "need" all the stuff. but just like racing. things happen. so having protection helps. as well as the sprocket, you dont "need" it. it just makes things easier.

like my bike for instance, stock sprocket i have to clutch it at like 12k to get it at balance point fast. where as, my +8 sprocket i only have to clutch at 6k. and also with stock sprocket its harder to keep it at idle when in a wheelie.

so, just as racers wear protective gear "in the event of a crash". stunt riders have protective cages "in the event of a crash". and as racers change gearing to get more power lowend or highend. stunt riders do it to get more lowend power. you dont "need" these things. it just makes it easier and more consistent.