Being competitive in a race means that you push your machine to its absolute limits. This applies equally to the motor and the chassis. Because of this, you need to make sure that your bike is in the best condition that it can be. You might be able to ride your bike on the street with a swingarm or steering head that is a little loose or worn, or with brake pads or tires with a few thousand miles on them, but on the race track any one of these things could spell disaster. Everyone knows that racing is a dangerous sport.
Racers accept and manage the risk.
Part of that risk management is proper bike maintenance. Don't add to your risk by riding a motorcycle in poor condition, or your bike could wind up hurting you or someone else. Proper preparation and maintenance are the keys to getting the most enjoyment from your investment of time and money. A poorly prepared machine is unsafe. You can expect the tech inspector to be very unsympathetic when examining a dirty or neglected motorcycle.