|SMPS can switch the input voltage from high to low|
The switching of a Switch Mode Power Supply has nothing to do with the input voltage, It switches the output voltage. Over current protection is a totally different thing altogether and can also be incorporated into a linear power supply if needed.
Early SMPS did not have over current protection and relied on the user setting the input voltage with a switch on the PSU. Get that wrong and you had problems.
Lightening can destroy a SMPS just as easily as any other kind of power supply. To protect from lightening you need a surge protector.