Yes there is a large inrush current surge into all the devices when the mains comes back on...charging up all the input capacitors.
This high current puts a lot of energy into the stray inductance of the mains grid wiring....when the inrush stops, the energy is still in the stray inductance, so it causes an overvoltage spike to all equipments.
If the mains grid wiring had zero stray inductance (impossible , i know), then there would be no bad surge problem when the power gets restored to the grid.
By "grid", i mean the "national electricity supply system."