The sonic boom of an aircraft overhead--and not coming in to land at that point--can be enough to dislodge tiling from houses. From a person in the middle of a group, there is a rather large chance that the undirected shockwaves would cause collateral damage (though probably not so badly as what happens when a normal person is moved at such speeds) and/or knock everyone over. Noise damage: bullets are generally supersonic, and they damage hearing. 

Showing up at supersonic speeds, from a scientific standpoint, is a bad idea if you have any concept of teamwork.