Since the 1980s, most electronic devices are powered by switch mode power supplies as opposed to older linear power supplies. Linear power supplies are less efficient but are not sensitive to changes in current. Switch mode power supplies are more efficient but are more sensitive to changes in current. MOV based surge protection cannot protection against surges in current so even when you think your surge protector is working, it may not stop the types of surges that damage today’s power supplies.
Additionally, more devices are made to consume less power, so their power supplies have become smaller. A smaller power supply is less able to resist the damage from everyday surges.
