Explain why in hospitals and polyclinics instruments are sterilized by boiling or heating in autoclaves at high pressure

Explain why in hospitals and polyclinics instruments are sterilized by boiling or heating in autoclaves at high pressure, and not by freezing? Low temperatures also kill the same microorganisms.

low temperature does not kill microorganisms, but only suspends their vital activity for a while (because in unfavorable conditions they form spores), but at high temperatures they die (I think this is due to the fact that microorganisms consist of protein, and at high temperatures the protein denatures , that is, it is destroyed).