Disagreement is fine but I hope you have evidence to back up that statement.
Autoclaves do not need to go above 300deg bc they utilize wet heat as I stated earlier. Wet heat can better and faster penetrate certain compounds and substances which is why they don't need to go higher than 300deg. Dry heat takes longer in most cases to raise the temperature enough to sterilize.
Please look at the following from the Center of Disease Control:
The basic principle of steam sterilization, as accomplished in an autoclave, is to expose each item to direct steam contact at the required temperature and pressure for the specified time. Thus, there are four parameters of steam sterilization: steam, pressure, temperature, and time. The ideal steam for sterilization is dry saturated steam and entrained water (dryness fraction ≥97%)813, 819.
Pressure serves as a means to obtain the high temperatures necessary to quickly kill microorganisms. Specific temperatures must be obtained to ensure the microbicidal activity. The two common steam-sterilizing temperatures are 121oC (250oF) and 132oC (270oF). These temperatures (and other high temperatures) 830 must be maintained for a minimal time to kill microorganisms
CDC - Disinfection & Sterilization Guideline:Sterilization - HICPAC
So I state again, the pressure is not what sterilizes. The pressure merely allows one to have superheated steam which is what sterilizes. Do you have any evidence to back up your statement?