>collision debris is not ejected into orbits that decay significantly slower than the original orbits, just due to how orbital mechanics work. True, but debris

>collision debris is not ejected into orbits that decay significantly slower than the original orbits, just due to how orbital mechanics work. True, but debris can (and has been) thrown into orbits with an apoapsis (high point) much higher than the original collision. Yes, the periapsis is still at the original altitude of the collision but the debris may collide with other satellites or debris creating secondary debris clouds at a much higher altitude than the original collision, and so on.