External Power Surges-  (Ex: brown outs, lightning, and utility work). If a lot of brown outs are occurring, turning computers or other important electronics off is beneficial because if these problems keep occurring, they can burn out or hurt the longevity of said electronics. Surge protectors take bad spikes from the accelerating current and deflects the spike to the surge protector, which protects your electronics longevity over time.  

Internal Power Surges-  Every time a continuous power source; when running for extended periods of time, (ex: heat, ac, dryer, washer, hot water heater, dishwasher, gaming consoles, tv, entertainment center, power tools, hair dryer) is used or turned on, the start-up amps spike in usage in a circuit. The initial spike is a surge, and it circulates through all of the loads in the panel, and over time damages the longevity of electronics.
Older appliances and heating sources cause more internal surges due to resistance in the circuit. This will cause the appliance/breaker to work harder upon start up and cause higher frequent running amps.