Source?
A CPU's and GPU's standard life expectancy are much longer than most people would even consider using them. They'd also run into other problems before damage, if any, from power fluctuation, would be noticeable.
Perhaps HDDs would be affected, but most have built-in fail-safes to prevent that. Cheaper ones may not.
I think usually it's the quality of the power supply that extends the life of your components, even if there was a power surge without a surge protector, the psu should protect the rest of the machine .