New: Sources tell me the attack on Natanz wasn't just about halting centrifuges. It appears to have been deliberately designed to destroy centrifuges, just as Stuxnet did yrs ago. Though this time, obviously, the weapon was kinetic rather than digital. https://theintercept.com/2021/04/13/iran-nuclear-natanz-israel/
Power is easy to restore even if electrical equipment is damaged, thus allowing enrichment work to resume fairly quickly. But an abrupt blackout that also takes out backup power would destroy some centrifuges, since they need to be powered down slowly and in stages.
Centrifuges spin at upwards of 100,000 revolutions per minute. Failure to power-down centrifuges slowly leads to vibrations that can cause centrifuge rotors and bellows to become damaged and in some cases disintegrate, which is what experts suspect occurred at Natanz.
Because centrifuges at Natanz facility are in halls buried more than 50 ft underground, beneath layers of concrete and dirt to protect them from an airstrike, it would have been simpler to damage them by targeting their power source, which in turn damages the centrifuges.
Here's video of a vibrating string, which shows what happens when spinning slows down - similar to what happens to centrifuge when it powers down. To control vibrations, you need to pause until centrifuge stabilizes, then proceed the shutdown in stages