Why can't modern electric and gas welding be used for the restoration of metal cultural relics, but can only use the traditional tin melting welding method?

The traditional welding method of molten tin can keep the metal cultural relics from being destroyed and its original shape, so as to achieve the purpose of protecting cultural relics. Although modern electric and gas welding technology is advanced, it also has its negative effects, that is, in the process of modern electric and gas welding, the buzzer and vibration process will more or less destroy the integrity of cultural relics, so it is not allowed to use modern electric and gas welding to repair cultural relics in principle.