Obviously nothing’s guaranteed, but yes, an electric toothbrush can prevent the need for restorative care. Just like a sealant can prevent an occlusal cavity, and silver diamine fluoride can prevent the extension of root caries in geriatric populations.
Yes, good technique with a manual can accomplish the same as an electric toothbrush. But poor technique with an electric toothbrush is lightyears ahead of poor technique with a manual toothbrush.
Question for you: how many people use good brushing technique? Answer: very, very few. How many of those same people would have fewer new cavities/less recurrent decay if they used an electric toothbrush instead of using a manual toothbrush improperly? Quite a few.
But then again, I’m only a dentist, so what do I know, QUATRO!?!