Some electric toothbrushes have these gimmicky features where they can map your mouth while you brush and report on your hygiene habits to tell you how effectively you're brushing, or even nag you if you don't brush enough. Guessing that's the kind they have.
So for the manufacturer, why allow the device to simply use a local account to track that information, when instead they can force you to register an account online and associate your brushing habits with all of the other shadowy telemetry data being collected about us online?
I think the complaint is that the start menu searches the Internet at all in the first place.