Comment by Aurornis

Apple has a unique market position due to their OS. A buyer shopping for a Mac can't visit multiple vendors and compare models.

Dell and Sonicare do not have that luxury. They are competing with other PC vendors and other toothbrush vendors.

The strategy is to produce so many models that you appear to serve every price point and need without requiring the user to shop around. You can find something in their lineup that fits your budget or requirements if you look long enough and you don't feel like you need to go looking around at competing vendors as much.

Having may models isn't a high cost because they share so many parts. I bet if you opened multiple Sonicare toothbrushes they'd share many main components like batteries or motors. Dell has a few laptop and desktop lines but they're different combinations of parts within a shared chassis.