Foot supports (parking brackets that come with bicycles) and mudguards (fenders) are dangerous equipment.
The removal of foot supports and mud protection is generally for road bikes, mountain bikes, and other high-speed running and off-road bikes on abnormal roads. Foot support and mud protection have their functions. Foot support can facilitate the support of the bike. The mud protection can effectively prevent sewage and mud from being thrown on the body. However, this two equipment also have their disadvantages and safety risks.
Disadvantages of foot support: bicycles supported by foot supports are not very reliable. You can observe it carefully. Usually, a strong wind blows on the road. Few bicycles supported by foot supports, even electric bicycles, and motorcycles, can still stand. Not fall. Then when the bicycle falls, it is very likely to damage the paint surface of bike or damage some parts, or even make the parts scrap. Even if there is no wind, artificial scratching and collision may dump your bicycle.
The safety hazard of the foot support: the foot support is movable. The strong vibration of the bicycle on the bumpy road will easily make the foot support lower by itself, especially the loose foot support that has been used for a long time. In this way, when you turn sideways at high speed or when there are protrusions on the road, once the foot support is opened, the foot support can easily touch the ground and raise the rear wheel of your bicycle, causing the bike to lose control and crash.
Therefore, I generally do not recommend riders to install foot supports, especially riders who like high-speed riding and off-road. When parking, please tilt your bicycle down to the left. Note: It must be the left side, because there is a fragile rear derailleur on the right side of the bike, and the bike is placed down to the left so that you can pick up the bike and step up from the left side (there are not many left-handers, right?)! There are also friends equipped with disc brakes when you put your bike down to the left, pay attention to the disc not to hit the protrusions on the ground to prevent the disc from being deformed by external forces.
About why mountain bikes are not equipped with mudguards, you can check the article "Why are mountain bikes not equipped with mudguards?"